A surface that shows, and a barrier that hides. The same word for what displays and what conceals.
Old French escren (a screen shielding against heat or light), of Frankish origin; the same word grew to name both a surface that displays and a barrier that conceals, since both are things placed to control what passes.
A surface built to be looked at, and the same word for what keeps something from being seen — display and concealment sharing one name.