Other mammals do not see colour as well as we do though most mammals see some colour, they may have only one or two pigments, or they may have different pigments to us altogether. Sometimes not every member of a species has the same pigments. Squirrel Monkeys have two or three pigments in their eyes, but they have five different pigments potentially available. It would make the evolution of a language to describe colour very difficult. Most mammals have a mixture of rods and cones in their retinas.
Most mammals also experience a variety of light conditions, night, dawn, day and dusk.
Therefore it makes sense to have a mechanism to control the amount of light that enters the eye. A way of ensuring as much light as possible reaches the retina under dull or dark conditions but capable of controlling the influx of light so that on bright day the sensitive retina does not get damaged by an excessive of light. This mechanism is called the 'iris', and it exists just outside of the lens. It is a circular sheet of muscle and through muscular control we can make its diametre larger or smaller and thus control the amount of light that enters the eye. Look into a friends eyes and see the size of their 'pupil'.