Number + 晚
As a noun, 晚 (wǎn) refers to evening or night. It is commonly used as a measure in phrases like 五晚 (five nights), typically when counting overnight stays. It can also appear in time expressions such as 今晚 (tonight).
我们在那个小岛上住了三晚。
wǒmen zài nàge xiǎo dǎo shàng zhù le sān wǎn.
We stayed three nights on that small island.
酒店预订了两晚,够不够?
Jiǔdiàn yùdìng le liǎng wǎn, gòu bù gòu?
The hotel was booked for two nights — is that enough?
他在朋友家待了一晚就回去了。
Tā zài péngyou jiā dāi le yī wǎn jiù huíqù le.
He stayed one night at a friend's house and then went back.