-(으)면 안 되다

The Korean construction -(으)면 안 되다 means "you should not" or "you are not supposed to."

Etymology

suffix -(으)면 ＋ adverb 안 ＋ verb 되다

Examples

먹으면 안 되요.

You shouldn't eat that.

만지면 안 돼요?

(asking for permission) Am I not supposed to touch it?

지금 만하면 안 돼요?

Am I not supposed to talk now?

그거 던지면 안 돼요? 유리예요.

You should not throw it. It is [made of] glass.