"¿Ustedes estudiaron para esta clase?"
Translation:Did you guys study for this class?
I’m confused because guys is informal English, so how does that relate to ustedes.
Ustedes is also used for informal you plural in most of the Spanish-speaking world. Other than in parts of Spain, you would use the ustedes form to say you to a group of friends, family members, children, etc., as well as to a group of strangers.