skatepark

The fact that most posters don't even know what a skatepark is---that's your answer right there.

He means a place to go skateboarding. Most kids simply skateboard in their compound. Al Jazi has some rails and even had a small half-pipe at one time (might be gone now if the kid has moved out). There is what looks to be like a half-pipe at the park on the corniche. Usually kids are sliding down it on their shoes. Also try the park near Landmark. Might be some stairs or other things that could be used to do tricks.
Unfortunately skateboarding is not well known here.