Stars emit colors of many different wavelengths, but the wavelength of light where a star's emission is concentrated is related to the star's temperature - the hotter the star, the more blue it is the cooler the star, the more red it is. Basically, the color of light that a star emits is somewhat related to its age, whereas the color of light that we actually observe from a star is related to the speed at which it's moving with respect to us. Now I read an article that says that the color of stars denote whether they are 'new' stars or 'old' stars.
According to Hubble, the color of stars can tell us whether the stars are receding from us and the speed of their acceleration.