会 (huì) means "to be able to" or "to know how to." It is used to describe a specific skill or ability that someone has. For example:
我会说中文。 (Wǒ huì shuō Zhōngwén.) - I can speak Chinese.
可以 (kěyǐ) means "to be allowed to" or "to have permission to." It is used to describe whether someone is allowed or permitted to do something. For example:
你可以坐这里。 (Nǐ kěyǐ zuò zhèlǐ.) - You are allowed to sit here.
能 (néng) means "to be able to" or "to have the ability to." It is used to describe a general ability or capability that someone has. For example:
我能做这件事。 (Wǒ néng zuò zhè jiàn shì.) - I am able to do this.
In general, 会 is used to describe a specific skill or ability that someone has, while 可以 is used to describe whether someone is allowed or permitted to do something, and 能 is used to describe a general ability or capability that someone has.