The verb ‘to be able to’ is an oddity in English, because we just say ‘can’ in the present tense, which is a lot quicker. For example, ‘I can play the piano’ means the same as ‘I am able to play the piano’, or ‘I have the ability to play the piano’.
When it come to questions though, there is a possible ambiguity in using ‘can’, and this depends on the context. For example:
Can you play the piano?
If this is a general question I might answer ‘Yes I can,’ i.e. I do have the ability to play the piano.
However somebody might be asking me if I would play the piano now, probably because there is a piano in the room and they already know that I can play it. The question is better put ‘Would you play the piano please Richard?’.
The English themselves often mix-up the use of ‘can, could, and would’, without misunderstandings. But to be clear, it’s best to use them as in the following examples:-
Can you show me how to get to the station? This is ambiguous, I might just answer ‘Yes I can’ (because I am able to do that), and walk off because I have answered your question.
Would you be so kind as to show me how to get to the station?