It’s used like sweating. We lose heat by havibg water evaporate off our skin. Right now get warm water and put it on your arm, then blow on it. It gets cold until it is fully evaporated. For water to change from the liquid to the gaseeous phase it needs energy. Think like water molecules are holding hands in a liquid. If one of them wants to come free and fly through the air it needs to somehow get the energy to break free from the grip of the others first. When water evaporates from your arm it tales this energy in the form of heat. It turns heat and uses it to get to the gaseous phase. As long as there is water on your arm it can be cooled that way.

That’s what data centers do as well. They take water to cool their processors and the let part of it evaporate into the air. That way the parts of the water that remain are like your arm - the get cool quickly.

It’s very effective. But if you live in a small town and next door there’s a massive datacenter that takes out all the groundwater and basically just boils it until it disappears, you might get angry after a while.