Digital devices - scanners, displays, cameras, printers, etc. - encode colors as numbers. Unfortunately, the meaning of a number for one device can be very different than that of another. This is one of the reasons a digital print can look so different from what is shown on a computer screen, or why an online portfolio looks different from one computer to another.
Color management addresses this problem by defining a universal language for describing color. Every color managed device has a translation to and/or from this universal language. It is therefor possible to translate colors between any color managed devices using the universal language as an intermediary.