Have you ever played with a puzzle where there are pieces that fit together perfectly, but they don't quite fit with any of the other pieces? Well, that's kind of like what's going on in the Basque Region of Spain.
There are a group of people who live there called the Basque people. They have their own language, culture, and traditions that are different from the rest of Spain. They want to be able to make their own decisions and be in charge of their own land without interference from the Spanish government.
Think of it like when you want to build a fort with your friends, but someone else tries to tell you how to build it or take over your fort. That's how the Basque people feel about the Spanish government.
Sometimes, the Basque people go to extreme measures to get what they want, like using violence or terrorism. However, many Basque people want to peacefully negotiate with the Spanish government to come to an agreement that will make everyone happy.
So, in short, Basque separatism is when the Basque people want to separate from the Spanish government to have their own independent country.