Can, like could and would, is used to ask a polite question, but can is only used to ask permission to do or say something ("Can I borrow your car?" "Can I get you something to drink?").

Is Can you please polite?

Both are correct. The first is more direct, and the second is more polite. Could you please . . . gives slightly more room for refusal than Can you please . . .

CAN is formal or informal?

The only difference between the two verbs is that one is more polite than the other. In informal contexts it's perfectly acceptable to use can; in formal situations it would be better to use may.