I understand it to mean that a person is guilty of the same thing she is accusing another person of, often in greater degrees than the accused, and so has no right to be derogatory to him. I like Wikipedia's synopsis: "As generally understood, the person accusing (the "pot") is understood to share some quality with the target of their accusation (the "kettle")." It also has the connotation of hypocrisy. Wikipedia gives a list of similar phrases, parables, and stories in English and other languages, such as the ancient Greek concept of "the Snake and the Crab," and the phrase, "those that live in glass houses should not throw stones."
I best like the explanation of the origin by commenter mark on answers.yahoo.com. He points out that regardless of whether the kettle is seen as black (as the pot is black) or polished metal, "for one to accuse the other of being black points out ignorance of oneself in accusing another (sort of, it takes one to know one)."
These are all common English words, so I would not find it difficult to read or pronounce. This question seems to have value only in comparing it to other idioms.
This idiom would only be used in informal situations. It often is used jokingly, but can be construed negatively, so one would want to have some familiarity with the listeners before using it. Our family has a variation we say to each other when one complains about something that is at least partially characteristic of the one complaining: "Hello pot, meet kettle!" I also sometimes use a variation of it to soften the impact when pointing out a problem with someone else: "I say this as a pot talking to the kettle" -- indicating that I am not being derogatory about the person, as I am guilty of, or perhaps struggle with the problem also.
I am a college-educated professional who works in the area of Information Systems (computers).
Apparently among the internet generation today, it is sometimes shortened to "pot, kettle, black." See also yahoo link above and the definition on the internet's Urban Dictionary.