How Do I find the X&Y Coordinates for an area of my map?

I have a Boss that I want to defend an area but I need the X&Y Coordinates!

I presume you are using creative mode.

I think you can’t do that in creative.
Try downloading UEFN and you’ll see, everything is much much simpler.

To obtain coordinates in UEFN, simply drag a new prop in the map and place it correctly. You will see the X, Y and Z position under the “Transform” details, that you can use to reference the spot where the boss should spawn.
Once you have the location you can remove the previously placed prop.

I don’t know if there’s a workaround in creative. Though, you should not be able to make custom devices in creative either.
Are you in UEFN?