In a world where over 6000 different languages are spoken, it is ever present how symbols and signs have become a universal language to convey information.
It is interesting to think that Safety Signs, Safety Stickers, Road & Traffic Signs have become a single language which many people all over the world can understand despite speaking a completely different languages.
It may well be easier to navigate the streets of a French town and obey an "arrêt" sign, than it is to buy a bottle of water, well for those of us who don't speak French anyway. The sign is identical in design and principle to our "STOP" signs.
Another common example would be a first aid sign.
The white cross on a green background is the universal method of marking the location of First Aid Kits, Trained Personnel or First Aid Stations.