In the green box, red and blue light is absorbed and in the blue box, green and red is absorbed so blue light is reflected. In the magenta box, blue and red light is reflected and green light is absent. In the cyan box, blue and green light is reflected and red light is absent. Finally, in the yellow box, red and green light is reflected and blue light is absent. Every color has its own meaning.
Some colors even have two or more meanings.
The practice of correct color selection is an art. One must know the meanings of all colors to make the right choices. Color research is extensive and results change as do the times. Different colors mean different things in different cultures. For example, in the United States, blue is considered to be a relaxing color.