Preparatory school (cram school) for entrance examinations — an institution providing intensive lessons and practice tests for exam preparation.
彼は大学受験のために予備校に通っている。
He is attending a cram school to prepare for university entrance exams.
予備校の授業は昼間の学校と両立するのが大変だ。
Balancing cram-school classes with daytime school is tough.
あの予備校は数学の講師が特に有名だ。
That cram school is especially famous for its math instructors.