what does "pave the path for sth/sb" actually means? and if possible, please provide some alternatives with the same meaning as well.
I'm not sure that pave the path is an idiom. I think that pave the way might be considered an idiom.
Pave the way for somebody/something means to make it possible or easier for someone or something to follow
Their governors and preceptors also should take care what sort of tales and stories it may be proper for them to hear; for all these ought to pave the way for their future instruction: for which reason the generality of their play should be imitations of what they are afterwards to do seriously. - Aristotle.
The figurative sense of to pave the way is attested from 1585.
One can easily imagine it is related to the path of least resistance in meaning. Alternatives are "make it easy", "clear the path", or "set the stage" for sth/sb.
The phrase is more commonly pave the way.
To pave is to cover something with material, such as stone, which makes it much easier to cover than muddy ground.
The idiom dates to at least 1585 and means that something has been introduced that allows something else to follow; to make it possible or easier for something else to happen.
For example, from a recent news headline:
Crucial vote could pave the way for Wrexham 'super-prison'
So if the vote is passed, the super-prison could follow.
As others have noticed, the idiom is "pave the way", though technically of course, both a path and a way can be paved.
Paving a path or road means you flatten it and put some kind of usually hard material on it, so that the path becomes easier to travel.
Figuratively speaking, when you pave the way for someone, you make it easier for them to do something.
Alternatives could be "help somebody to do something", "enable them to do something", "create the prerequisites for someone doing something".
An idiom in the same direction could be "show someone the way to do something", although this implies some teaching, whereas paving the path does not necessarily have that connotation.
While several answers point out the idiom pave the way suggests that a paved road is easier to walk. However, you really need to conjure images of tradesmen, armies, simple foot traffic slogging in mud in a rainy season to appreciate the importance of the Appian Way and how much advantage a paved path gave to Roman commerce and conquest. Many other cultures, before and after, similarly found paved roads to be their critical arteries.
An alternative idiom in the same vein is lay the groundwork.