The correct answer to this open question is the following.
The way I would explain the colors to Gerald is by sketching out an imaginary shop, including the colors to differentiate the areas Gerald could understand the way colors are used.
According to OSHA, the Occupational Safety and Health Administration, every factory, business, shop, and office must identify different zones of risk through the use of colors.
Signs with color red menas fired-related hazards, hot water, hazardous objects or machines, fire alarms, the sign of an exit.
Signs with the color yellow is to indicate "precaution." To be aware of, watch your step, stumbling, or tripling. It is a color to indicate precaution and avoid injuries.
Signs in orange are to identify potential risks with an added explanation. It is not too great a risk such as in the case of the color red, but it needs to communicate that there is a risk with consequences. Example: low clearance levels or electrical hazards.
The green color indicates general messages or important messages to be aware of. No specific risk or danger. Just to inform people to be alert. This color suggests good practices in the workplace.
The blue color indicates informative messages unrelated to risk practices.
Messages such as "show your ID all the time," or sign in, before entering."