What does it mean when a guy flirt with you?

Answer 1

Usually, it means that he's developing a crush on you, but he's not sure yet. He cares about you as a friend, but he's just beginning to see you as a potential girlfriend. Here's some advice: Don't flirt back unless you like him back(!)

Answer 2

It means he is probably interested in you, either physically or personally, or both.

Answer 3

It may mean that he likes you.

He probably likes you or is just a big flirt