for me court sense is knowing what's happening on the court at all times. where you are exactly, how far you are from the baseline, where your opponent is, where you can hit the ball...an open space or something like that. those things...also, how well the ball bouces, and where the lines are even when you're not directly looking at them... and it's very improtant too if you're gonna win your matches...sorry if that doesn't really help
but that's all i can think of to type right now...
At it's most fundamental, court sense is spatial awareness. Knowing exactly where the court stops and starts, and where you are on it. Sounds simple, but if you've ever tried to park a car in a small space you'll realise that being aware of a physical space in that way isn't easy at all!
But the phrase "court sense" also includes the idea that you know where your opponent is, where he/she is about to hit the ball, and can do this in time to get yourself in position.
So basically, what I'm saying is that court sense is about a physical sense of the court and anticipation of your opponent.