Er...what can I say??
Except "I'll just get on with the meaning?"
OK, then. I'll just get on with the meaning.
Meaning & EtymologyEdit
Basically, it means, "it's your choice". It comes from tennis, obvioiusly, from when one's opponent hits the ball back and you have to decide where to hit it (out of one's opponent's reach is advisable).
Use in Normal SpeechEdit
When explaining a choice
"So, either stay on campus or off campus. The ball is in your court. You have to stay there, so it's your choice and nobody else's."