、。
After dinner, I study my schoolwork for three hours.
Literal
Dinner-after [topic-は] 3-hours, school-subject-of study [object-を] do.
学課 ('school lessons, curriculum') is a slightly uncommon word — usually rendered as 授業 ('class') or 勉強 in everyday speech. Here it refers to the school subjects one is studying. 三時間 is the duration form: quantities of time attach without a particle when used adverbially. The sentence is a small window into a disciplined student's routine.