Formal:
* চুপ করে থাকুন (chup kore thakun) - This is the most formal way to say "be quiet". It literally means "stay quiet".
Informal:
* চুপ কর (chup kor) - This is a more informal way to say "be quiet". It literally means "become quiet".
* শান্ত হো (shanto ho) - This means "be calm", and can also be used to mean "be quiet".
* নিশ্চুপ থাক (nishchup thaak) - This means "stay silent".
Other:
* কথা বলবেন না (kotha bolben na) - This means "don't speak", which can be interpreted as "be quiet".
The best way to choose which phrase to use depends on the situation and your relationship with the person you're speaking to.