A (school) class; the grouping of students into a class unit (used for things like homeroom, class representatives, etc.).
今年の学級は人数が多く、賑やかだ。
This year's class has many students and is lively.
学級委員に立候補した生徒が二人いる。
Two students ran for class representative.
流行のため学級閉鎖になり、授業がオンラインに切り替わった。
Due to the outbreak, the class was closed and lessons switched to online.