Light is a range of electromagnetic waves.

Our eyes translate certain wavelengths of light into specific colors.

Colorful objects absorb certain wavelengths and reflect others.

Chlorophylls, for example, do not absorb between 500 and 600 nm and therefore they are green. They have two characteristic absorbance peaks at around 450 and 650 nm.

Carotenoids absorb a wider range of wavelengths, ranging from 400–550 nanometers (violet to green light). This causes the compounds to be yellow, orange, or red.

Phycoerythrobilin appears red because, due to the seven double bonds in its main conjugated system, it absorbs mostly green.

Have a good look at the solar spectrum. Visible light actually comprises a narrow range of wavelengths, from about 390 to 700 nanometers!