I_need_player_pos
Objects that are made from the Control class, like buttons, panels, and rectangles, have a rect_position property that gives a Vector2 with the x and y value of the control. Objects that are made from Node2D, like sprites and tilemaps, have a position property that does the same. So if you have a script on the object, you just have to assign the property to a variable.
var pos = rect_position
If you want the position in another script, you could refer to it with
var pos = $my_object.position
You can see this in the first game tutorial in the documentation.