It's a phrase expressing the desire for someone to return. It's often used in a romantic context, but it can also be used for other situations where you want someone to come back.
Here are some examples of how it can be used:
* Romantic: "Te escribo esta canción para que tú vuelvas." (I'm writing you this song so you come back.)
* Friendship: "Hice tu comida favorita para que tú vuelvas a visitarme." (I made your favorite food so you come back to visit me.)
* General: "Espero que la lluvia pare para que tú vuelvas a casa." (I hope the rain stops so that you can come back home.)