Number + Unit + 高
高 (gāo) means tall, high, or height. When used after a measurement, it indicates how tall or high something is, as in 15米高 (15 meters high). It can function as an adjective, noun, or complement depending on the sentence structure.
这栋楼有五十米高,是这一带最高的建筑。
Zhè dòng lóu yǒu wǔshí mǐ gāo, shì zhè yídài zuì gāo de jiànzhù.
This building is fifty meters tall and is the tallest structure in the area.
那座山海拔三千米高,爬上去需要两天。
Nà zuò shān hǎibá sānqiān mǐ gāo, pá shàngqù xūyào liǎng tiān.
That mountain is three thousand meters above sea level; it takes two days to climb up.
新建的那座塔大约有二十米高。
Xīn jiàn de nà zuò tǎ dàyuē yǒu èrshí mǐ gāo.
The newly built tower is about twenty meters tall.