Villagers are a very interesting, and confusing topic in Minecraft, villagers are mainly used for trading, you can get useful, or rubbish items from villagers in exchange for Emeralds.
Villagers have an evil counterpart,pillagers, pillagers can spawn randomly in your worldor they will be in a naturally generated structure called
this is what a villager looks like:
villagers spawn in villages,and if there are monsters nearby, the villagers will spawn an iron golem, an irom golem is a very strong mob thathas lots of health and deals alot of damage if you hit him, so be aware!
Here's all the types of villagers and what they need to obtain that job:
there is a certain type of villager called a nitwit, these villagers have green coat and they can not learn a job