A lots of stuff: M16A2, obstacle course, a lot of PT (Physical Training), a lot of military study, history about the marines, military standards, military laws (USMJ), hand to hand combat, bayonet training, Drills (matching), etc.
Brainwashing aside, I think it's great training. It trains a civilian how to live properly. I used to get up pass 12pm, sleeps at 4am. My life is a mess, zero organization, very inefficient. Military trains a person to live efficiently, I learned to fold my bed, clean my barrack, get myself ready to go in less than 10 mins. I do things a lot faster and waste less time and energy than I do as a civilian. I get up at 0330 and go to bed at 2000, I get more sleep than I do when I am a civilian. Very motivated and full of energy, which I like very much.