With our eyes we can sense (perceive) a very narrow range of vibration frequencies of ElectroMagnetic (EM) vibration corresponding to wavelengths from 0.3 to 0.7 micrometers - from purple to red. A mix of the vibration frequencies in the above range we perceive with our eyes as color. We can measure this mix precisely by recording a spectrum of light, but only using special instruments, called spectrophotometers.
Colors perceived by our eyes are only our partial perception of MUCH more complex reality : complex vibration of light (and other vibrations as well). To explain the above statement, we would need to define the spectrum and explain how we perceive color with our eyes.