This is one of the aircraft runway signs, renamable. Place it in Surveyor and click on the ? button in the menu then the model. An explanation screen opens showing a diagram of the types of signs used on runways, and for which one this is suitable. Type in the required letters or numbers in the box at the top of the screen.
This sign is suitable for number 1 Taxiway/Runway Hold position, 2 Runway/Runway Hold Position or 4 ILS Crirical Hold Position.