My brother loves playing something called cue sports but I don't know much about what that is. Is it like golf or pool?
It's basically a broad term for a variety of games of skill generally played with a cue stick, like billiards or pool for example.
Oh awesome. Is it a popular sport in the United States?
I think it's a fairly niche sport to be honest, I know that billiards means different things depending on if you're in Britain or the US though, oddly enough.
Oh does it? I don't really know what billiards is. I do know pool pretty well though. 
I think they're pretty similar, billiards has quite a long and rich history though, it was first created in the 15th century for instance.
Wow that is a long time ago! Are there tournaments or anything?
Yes there are definitely professional pool tournaments, surprisingly even Babe Ruth and George Washington were billiards fans!