In a liquid, water molecules were in a low energy state because they were strongly attracted to its neighbors. When water evaporates, energy is removed from the liquid water. In addition, when water does evaporate the fastest molecules leave first. The molecules left behind are slower. For both of these reasons evaporation is a cooling process.
Humans use evaporation of water, sweat, to cool their bodies.
The evaporation of a small amount of water produces a large cooling effect.