Within the visible light of the electromagnetic spectrum are still more wavelengths. Each wavelength is <u>perceived</u> by our eyes as a different color. The shorter wavelengths of visible light are violet — we might call them purple. Then as the wavelengths get longer and longer, the visible light changes in color to blue, green, yellow, orange, and finally the longest, which is red.
Some animals can see waveslengths of light that humans cannot. Those waveslengths would be just outside the edges of human visible light. For example, insects can see ultraviolet waves — waves just before purple on the electromagnetic spectrum. But we are not able to see these. At the same time, there are colors of red that insects are unable to see, but that humans can.
Hope this helps :)
