Move a selection to specific X,Y position in Photoshop

With your active selection, go to Edit » Free Transform. This is the same as pressing Ctrl-T on Windows, or Cmd-T on OS X.

Then, in the toolbar above your image, select the angle point where you want to set the coordinates. In my example, it is the center of the selection.

Now, enter the X and Y coordinates you want your selection to be at. If you want to move your selection relative to the previous location, toggle the triangle button.

Hit Enter or click the "Commit transform" button (which looks like a checkmark).