Okay kiddo, imagine you have two groups of friends who don't really get along. Every time they're near each other, they start fighting and causing trouble. Now imagine that you're the teacher in charge of these kids, and you don't want them to fight anymore.
To prevent them from fighting, you decide to put a buffer between them. This buffer is a neutral person or thing that can keep both groups separated and prevent them from coming into contact with each other. It's kind of like a "no man's land" that both sides agree to stay away from.
In the same way, a buffer state is a country or region that acts as a neutral area between two larger, potentially hostile countries or regions. This buffer state isn't a part of either country or group, but it's located between them and helps prevent conflict or tension by keeping them separated.
The purpose of a buffer state is to prevent war, create peace, and maintain stability between two larger powers. It's kind of like a peacekeeper, keeping both sides away from each other and preventing any dangerous situations from happening.
Does that make sense, kiddo?