可以, 能 and 会，let's take "我可以说中文" , “我能说中文” and "我会说中文“as examples。 All of them have the meaning of "I am able to speak Chinese". The differences are: "可以” : I am able to speak Chinese, but I am not really sure about my Chinese level. - Less sure. "能" : I am able to speak Chinese, and I have confidence in myself. - More sure. "会" : I am able to speak Chinese, because I'm a native speaker or I've learnt Chinese for 10 years. - Completely sure. “会” is more "natural ability" or "completely acquired that ability, it has become your ability now“. "能“ and "可以” is more "gaining the ability through learning, but you're not ready". 可能 is maybe,that's it.

可以 = can; may. 能 = ability; able; can; be able to 可能 = possible, maybe These are the most common meanings. There are other meanings to these words too depending on how it's used. It would be best to look these up in a dictionary and look at a few sentences with these words in it to make more sense of it. It's part of the learning process!