The idiom "hit the sack" means:

• Hit the sack/hay:
English Meaning: to go to bed in order to sleep:
Bangla Meaning: শুয়ে পড়া; ঘুমাতে যাওয়া।

Example sentence:
- I’ve got a busy day tomorrow, so I think I’ll hit the sack.
- After a long day of work and errands, John decided to hit the sack early to get a good night's rest.

Source:
1. Cambridge Dictionary.
2. Accessible Dictionary by Bangla Academy.