"We need two people."

Translation: Potřebujeme dva lidi.

[gSee4]

Why is My potřebujeme dva člověka wrong

[HK-FTW]

'lidi' is usually used to describe people in general but 'člověk' is more of a scientific term (human)

e.g. 'člověk vs. šimpanz' = 'human vs. chimpanzee' not 'lidi vs. šimpanz'

[ValaCZE]

It is same as in english man (person) X people). In czech člověk X lidé.