How do you know if a guy likes you?

Theres this guy that i've had a crush on. My cousin said that he told him that he likes me abut a month ago. But i saw him again a few days ago and he started to be really mean wit my cousins. Then yesterday, i went over his house without my cousins and he would try to get my attention and call me "baby boo" and make me laugh. Is he trying to get my attention or does he like me?