How does drinking water help with weight loss?

I am 19 and am a male and when I asked about losing fat in particularly, and a lot of people said for me, drinking a lot of water throughout the day will definitely help.

So I ask, why and how does drinking plenty of water throughout the day (some say 2–4 liters) help with weight loss? What is the science behind it and the basic (in lamense terms) answer behind it?