Number + 小时 (+ 后/前)
The word 小时 (xiǎoshí) is the standard Chinese word for "hour" as a unit of time. It is typically preceded by a number and can be followed by time-related words like 后 (after) or 前 (before). For example, 三小时后 means "after three hours."
从这里开车到机场大概要两个小时。
Cóng zhèlǐ kāichē dào jīchǎng dàgài yào liǎng gè xiǎoshí.
It takes about two hours to drive from here to the airport.
她每天花三个小时练钢琴。
Tā měitiān huā sān gè xiǎoshí liàn gāngqín.
She spends three hours every day practicing piano.
再等半个小时,他们就到了。
Zài děng bàn gè xiǎoshí, tāmen jiù dào le.
Wait another half hour and they'll be here.