Evaporation is when liquid turns to gas
Evaporation is when particles escape from a liquid.
Particles can evaporate from a liquid at temperatures that are much lower than the liquids boiling point.
Particles near the surface of a liquid can escape and become gas particles if: The particles are travelling in the right direction to escape the liquid. The particles are travelling fast enough (they have enough kinetic energy) to overcome the attractive forces of the other particles in the liquid.
The fastest particles (with the most kinetic energy) are most likely to evaporate from the liquid~so when they do the average speed and kinetic energy of the remaining particles decreases.
This decrease in average particle energy means the temperature of the remaining liquid falls - the liquid calls.
This cooling effect can be really useful. For example you sweat when you excercise or get hot. As the water from the sweat on your skin evaporates, it cools you down.