Okay kiddo, so Sabine Free State is a place in the United States, more specifically in the state of Louisiana. A long time ago, when Louisiana was still a territory and not yet a state, there was a dispute over who owned a big chunk of land in the western part of the state. Some people said it belonged to Texas, while others claimed it was part of Louisiana.
So some people who lived in that area decided that instead of waiting for the government to decide who owned the land, they would just declare their own independent state! They called it the Sabine Free State. They even made their own money, with pictures of their own president on it.
But the fun didn't last too long. The people in charge of Louisiana and Texas eventually decided the land belonged to Louisiana, and they sent soldiers to enforce the law. The Sabine Free State was forced to disband and join the rest of Louisiana.
So while it was a cool idea, in the end it didn't work out because it's not allowed to just declare yourself an independent state without permission from the government.