别⋯⋯了
bié …… le
Expressing "stop doing" with "bie… le"
别…了 tells someone to stop something they're already doing.
别 + Verb + 了
How it works
别哭了 — stop crying. Without the 了 it would mean "don't cry" to someone who hasn't started.
The 了 is the change-of-state particle: it asks for the current situation to end.
不要…了 works identically: 不要说了.
Examples
bié kū le
别哭了。
Stop crying.
bié shuō le, wǒ zhī dào le
别说了，我知道了。
Stop — I get it.
bié wán shǒu jī le, kuài chī fàn
别玩手机了，快吃饭。
Put the phone down and eat.