why do table tennis players say cho

"Cho! " is a common Chinese phrase that some players yell out after winning an intense point. Etiquette Tip: Cho's should be used sparingly. Constantly cho'ing, cho'ing at the top of your lungs, and cho'ing after winning a point by an edge ball, net ball, or opponent's unforced error is widely considered rude or inappropriate.
Why do professional players say Choi after winning a point?

What is the call that players make after winning a point?

It sounds like "cho" or "choi".

Is it Chinese and what does it mean/translate as? None of my table tennis buddies know this. Thanks. Richard, thanks for your question.

Professional players use many different methods to "gee themselves up" or "psych themselves up" so that they can concentrate on their own game and play to their full potential.

Making a noise after winning a point is just one method. The noise/word doesn't mean anything in particular. It's just self encouragement.