good night = 晚安 [Wǎn'ān]
Two little peanuts lie side by side in their open shell and say good night. Then the shell closes over them like a blanket, and soon there is only snoring: 晚安.
晚安 (wǎn’ān) means “good night.” 晚 is evening and 安 means peace, so it wishes someone a peaceful night. Use it when someone is going to bed, not as a greeting.
To say “good evening” when you meet someone, use 晚上好 (wǎnshang hǎo). In the morning it is 早上好 (zǎoshang hǎo) or 早安 (zǎo’ān).
晚安，明天见。 — Wǎn’ān, míngtiān jiàn. — Good night, see you tomorrow.
我要睡觉了，晚安！ — Wǒ yào shuìjiào le, wǎn’ān! — I’m going to bed. Good night!