What College Options Does An Active Duty Soldier Have?

He wants to take some classes, and he heard that there is an option where he can be active in the Army but still go to college 2 days a week, or something along the lines of that. Does anyone know anything more about this option, and other options he has? I know he could take some online classes but would he get time off from work for them? (I told him I’d research it all for him for when he got back from the field). Thank you!