Okay, so you know how when you want to use something, like a toy or a game or a computer program, you usually have to follow some rules? These rules tell you how you're allowed to use the thing and what you're not allowed to do with it. For example, you might have to ask your parents before you use your tablet, or you might not be allowed to play with a certain toy outside because it could get lost or broken.
Well, 0bsd is a set of rules that people who make computer programs can choose to use. It's called "0bsd" because it's a type of license that has zero rules! That means that people who use programs with 0bsd can pretty much do whatever they want with them, as long as they don't break any laws.
So why would someone want to use a program with 0bsd instead of a program with lots of rules? Well, sometimes it's just easier. If you don't have to worry about following lots of rules, you can use the program in any way that works best for you. Plus, if you want to change or improve the program, you have more freedom to do that with 0bsd.
Overall, 0bsd is just a type of rule (or lack of rules) that people who make computer programs can choose to use. It lets people use the program in any way they want, as long as they don't break any laws.