A fire screen began as a form of furniture that acted as a shield between an occupant of a room and the fireplace, and its primary function was to reduce the discomfort of excessive heat radiating from a log fire. Early firescreens usually were shaped as flat panels standing on attached feet, or as adjustable shield-shaped panels mounted on tripod table legs.

Firescreens in the modern home have become decorative shields of sheet metal, glass, or wire mesh that can be placed in front of a fireplace

Fireplace

A fireplace is an architectural structure to contain a fire for heating and, especially historically, for cooking. A fire is contained in a firebox or firepit; a chimney or other flue allows gas and particulate exhaust to escape...

opening to protect the room from open flames and flying embers that may be emitted by the fire.

Fire screens were used to cover the fireplace when nothing was burning inside it. They were used to make what could have been a boring hole in the wall look more decorative.