Translation:Éva runs over to Kati and Péter, and they play.
What is the difference between runs TO and runs OVER TO in this sentence?
It mainly means that Kati and Péter are not in the immediate area, but a little further away. In the neighbour's garden, for instance.
The Hungarian prefix oda- also carries a sense of completion: Éva will end up playing with her friends. We're looking at the entire process instead of just at the "running" part.