Ver las estrellas = To see stars*

To be in pain after hitting yourself with something.

Usually, it is the result of an accident and it refers to the fact that you may see flashes of  light as a result of the impact.

"Se dio un golpe que le hizo ver las estrellas" .

"Al chocar con el cristal,vio las estrellas".

"Te voy a dar una torta que vas a ver las estrella