Primarily refers to a weekly school timetable showing subjects and periods. Can also be used more broadly for any fixed schedule, but the school context is dominant.
I received the new semester's timetable.
明日の時間割を確認しておいてね。
Make sure to check tomorrow's schedule.
Putting together the timetable for the new semester is a lot of work.
The students move between classrooms according to the timetable.
The timetable is set to change starting next month.
Every morning I check the timetable before preparing my textbooks.