Number + 面 + Noun
面 (miàn) means "side," "surface," or "aspect" and is used as a measure word or noun. It can refer to a physical face or surface of an object, and also serves as a measure word for flat objects like flags or mirrors.
这面墙需要重新刷一下漆。
Zhè miàn qiáng xūyào chóngxīn shuā yīxià qī.
This wall needs a fresh coat of paint.
问题有很多面,我们不能只看一面。
Wèntí yǒu hěn duō miàn, wǒmen bù néng zhǐ kàn yī miàn.
Problems have many sides; we can't just look at one side.
广场上挂着一面很大的国旗。
Guǎngchǎng shàng guàzhe yī miàn hěn dà de guóqí.
A very large national flag is hanging in the square.