The Prague Linguistic Circle is a group of people who meet to talk about language. Just like you talk to your friends about your favorite things, these people talk about the way we use words and sounds to communicate with each other.
They have lots of different ideas about how language works, and they study it very carefully to try and understand it better. They think about things like grammar (the rules of a language), how words sound, and how people use language to express their thoughts and feelings.
The Prague Linguistic Circle started in Prague, which is a city in Europe, a long time ago. They wrote a lot of books and papers about language, which helped lots of other people learn about it too.
It's like a club for people who love language, and they all work together to understand it better.