A likable person is agreeable and friendly. It's very easy to be fond of someone who's likable.
Every student wants to take a class with the most likable teacher in your school, and your likable acquaintances find it easy to make friends. In books and movies, the characters who are the most sympathetic (and who we tend to root for) are the likable ones. You can spell this adjective with or without an e: likable and likeable are both correct.