A grille is a series of bars that form an open barrier or enclosure. Grilles allow air and other gases to pass freely from one area to another.
Venting grilles cover ventilation holes but still allow air to pass through the opening. They protect against items falling into holes or coming into contact with dangerous ventilation fan blades.
Venting grilles are used in the construction industry to ventilate buildings. Automobiles, appliances, and other heat-generating devices use venting grilles to transfer air safely from one area to another.