(x,y) is not a simple constant, but at least two constants (x, and y). What kind of 2D array do you have.
Does it have exactly two columns (or rows) and do you want to subtract e.g. x from row 1 and y from row 2, for example?
Of course if the elements of your 2D array are e.g. xy clusters, you can just subtract the single xy cluster with an atomic subtract node. Other cases might need a loop.
Your question is not clear. Please attach a small VI containing typical data. Thanks!