ワードアップ英会話 WORD UP ENGLISH CLASS | 日記 | Idioms "hit the books"
2017/03/28 Idioms "hit the books"
The idiom "to hit the books" simply means "to study," often with the nuance of studying hard.
So, for example:
Suzie: I'm going out for dinner and drinks with some friends tonight. Do you want to come? Keiji: I'd love to, but I can't. I have a big test tomorrow, so I have to hit the books. --Here, Keiji means that he has to stay home and study hard for his test.