Pronoun/Human Noun + 们
们 (men) is a suffix attached to personal pronouns and certain human nouns to indicate plurality. For example, 你 (you) becomes 你们 (you all), and 朋友 (friend) becomes 朋友们 (friends). It is only used with people, never with animals or objects in standard usage.
同学们都在教室里等着。
Tóngxuémen dōu zài jiàoshì lǐ děng zhe.
The classmates are all waiting in the classroom.
你们先走吧,我等一会儿。
Nǐmen xiān zǒu ba, wǒ děng yīhuìr.
You all go ahead — I'll wait a bit.
朋友们给她办了一个生日派对。
Péngyǒumen gěi tā bàn le yīgè shēngrì pàiduì.
Her friends threw her a birthday party.