It's a common Spanish phrase used in various ways, including:
* To confirm something is already known: "Ya sabes, it's going to be a long drive."
* To introduce a new topic: "Ya sabes, I was thinking about that project..."
* To show understanding: "Ya sabes, I've been there."
* To express familiarity with something: "Ya sabes, that's my favorite restaurant."
The exact meaning can vary depending on the context.