People can differentiate between around 10 million various colors, so it’s easy to assume that the mirror is silver or white, since we can’t see its color. The answer is a little different, though.
A perfect mirror would reflect any image precisely, at the correct angle and distance, and its color would be a kind of white.
Since we don’t live in a perfect world, real mirrors absorb a certain amount of light.
Mirrors reflect the light in the 510 nanometer range the best, which belongs to the spectrum of visible green light.
Your mirror is therefore technically light green.