I'm Italian and I'm trying to improve my English, but I have some difficulty speaking with and understanding people of different countries.
For example when I study English in books it seems to be easy to learn, but when I have to use it at work with people of different countries I have a lot of problems.
So the question is: what is "real" English? Where can I study it? It is good to watch some films in English or would that teach me "bad" English?
Despite the fact that there exist many varieties of English, the vast majority of spoken media is in the General American or in the Received Pronunciation of British English. Written media is pretty dialect-free (again the great majority).
So your difficulty is probably understanding spoken language in a casual atmosphere. It could be that the people you hear come from a variety of backgrounds, but they will most likely be aspiring (if ESL speakers) to one of American or British pronunciation.
So the first step is to pick one of those. The general point is that no choice is wrong but making a choice now will solidify skills in one, to make learning the other one easier later.
As you say, movies (and TV) will teach you good pronunciation as far as accent. Yes, too casual speech (slang) might be confusing, and you don't want to learn profanity inappropriately (which is almost always). But one can often find online transcripts so that you can read along. Actors in TV and movies do tend to articulate well and in the standard. Some movies might use a 'bad' variety (mumble too much or be too casual/slangy/taboo), but most are not. Comedies might be hard because of word play, but then that would be a good learning lesson too.
News reports are good too because their pronunciation will be very articulate. Start with TV news rather than radio, because it will give semantic context with the pictures, which will help disambiguate unsure vocabulary.
A growing, very easy resource is youtube videos. A lot of it is amateur, meaning, not produced with expectations of high quality and experienced actors. It will be more casual and conversational, more likely to have dialect/pronunciation variations, but the real challenge is the natural slurring, mumbling, rushed lack of distinct articulation. I'd suggest sticking with the more professionally produced youtube videos before graduating to the real-life speech of the amateur (which is eventually what you really want to learn).
But frankly, don't leave something out if its easy to do. That is, listen, listen, listen. (Talking too is very important, in fact terribly important, the more you try to talk the more practice in your head you'll be doing and you'll be able to understand more that you hear)
It seems to me you do not have a lot of listening-exposure to spoken English. Listen to radio shows, movies and any other sources of spoken English more. Hearing comes over time and speaking will follow as well.
Your classroom studies seem to have provided you with a good base already. Now it's time to test it in the field and grow more.
Every region speaks English a bit differently and pronounces words differently. Some speakers will speak quickly and mush words together, or will slur the pronunciation of certain words. Some dialects leave out certain letters (In North America, various British dialects are infamous for H-dropping or turning T into glottal stops). Each region will have different terminology that is favoured, or different vowel pronunciation for the same words, or sometimes even different grammar (Part of the US uses a construction that most other English speakers consider ungrammatical: They say something like "This car needs washed", whereas others would say "This car needs to be washed". To the inhabitants of that region, the sentence is fine, to others, wrong).
In short, there is a lot of variety. As a new learner, you should learn about the varieties, but you only really need to focus on mastering one dialect/accent. That's what native speakers do. You can work on understanding the other dialects as you gain proficiency. Even native speakers can have trouble with other dialects/accents. As a native speaker from Canada I wouldn't even bother trying to speak the same as they do in Scotland, or Texas, or India. I'd just try to understand their pronunciation and pick up their local jargon words.
(I am using the word "dialect" here loosely, I don't really consider them to be separate dialects).
Linguistically, there is no such thing as "real" English. Every dialect is as valid as every other dialect, as long as the speakers understand one another.
There was a time when people in Italy spoke accented Latin. Later, they spoke such odd Latin that people from other parts of the former Roman empire couldn't understand them. At some point, this weird Latin dialect got a name: Italian. The same is true for French, Spanish, Portuguese, etc.
The same thing could be happening today (though probably not, because of the ease of travel, the internet, etc). The dialects of England, Scotland, The United States, etc, could be diverging so much that eventually we'd call them different languages.
Sure, as a native speaker, I can distinguish "educated midwestern US English" from "lower-class New York English". But that doesn't make one more real than the other.
So, rather than ask which dialect is "real" English, I'd advise you ask "how can I learn to understand and talk with English speakers from different places?" And the answer is, talk with them, watch movies, listen to music, and in general expose yourself to everyday language as much as you can.
In addition to studying books on the English language, you will also need to learn what is known as "Conversational English".
Please note that there is no "Standard English", let alone one "real" English when it comes to conversation with/ among people from different places. You can see that your questions is tagged with at least four tags "American-English", "British-English", "dialects" and "early-modern-English"!
It may be a good idea to focus on one dialect and spend time with people who speak that dialect, observing and participating in their conversation.
I am sure, with a little patience, you will get more useful ideas right on this page, so keep coming back.
