What does "cooks crystal" mean?

I haven't seen the movie, but it sounds like she's talking about crystal meth, aka methamphetamine. So, roughly:

Jack: So he works here?

Sandy: Yeah, but it's just a cover. He makes drugs.

EDIT: IMDB seems to agree.

She tells Reacher that she pretty much did whatever Jeb told her to do. She said Jeb was supposed to be an employee at the same auto parts store (he hadn't come in to work that day), but she said he really made his money from crystal meth.

From the Drug Slang Dictionary:

cook - Drug manufacturer

crystal - Cocaine; amphetamine; methamphetamine; PCP

He manufactures a popular drug that has a crystalline composition.