I just had a tile shower stall put in and the guy that put it in did not fix the floor right for the water to drain out what can I do about it or what will happen to my shower stall with the standing water?

The tile wasn't sloped to the drain?
How long ago did he install it?
Have you called him?
You may have to sue him for a very expensive repair. Redoing a tile shower floor is difficult. If he installed a flat floor, I wouldn't want him to do the repair; I'd want my money back and hire someone else.

What will happen? Mold, mildew, accumulation of crud and very unsanitary condition.

About the only fix is to tear out and redo.

... also, discoloration of grout and "mapping" on the tile. Deal with it now. Call the guy back to rework it. If he is honest contractor, he will do the repairs free of charge to you.

Let us know what happened. Thank you. Milo