Assignments that teachers give to students to finish at home. These can be short-term questions or long-term projects, but both are due by a certain deadline.
For Japanese students, one of the noteworthy homework is that in the summer vacation. They take this long vacation in the middle of the Japanese school year (starting in April), so teachers give them some amount of homework. You should work on it little by little, or you end up with the homework hell in the end of the vacation.