What kind of (something)?
"What kind of ___?" is a way to ask for more details about something. For example, if someone tells you that they like hip-hop music, you can ask:
What kind of hip-hop?
You're asking to hear more details about the specific genre or style of music.
As another example, imagine that you're talking with a coworker about what food he likes to cook.
A: I do a lot of baking.
B: Baking? Really? What kind of baking? Like bread, or like cakes and cookies?