It is the range of electromagnetic waves that you can detect with your eyes.
Wavelength
Visible light has wavelengths around 750 billionths to 400 billionths of a meter. It has kind of like the normal range of the wavelength and either changes to get longer or shorter. If it was going in the spectrum order, it would change to a shorter wavelength. The different colors in visible range from short-wavelength in blue to long-wavelength in red.
Energy
Light is basically energy that you see, and feel. Your eyes contain substances that react differently to various wavelengths of visible light, so you see different colors. When all of the colors are present, you see the light as white
Frequency
A typical human eye will respond to wavelengths from about 390 to 700 nm. In terms of frequency, this corresponds to a band in the vicinity of 430-770 THz.
ROY G BV/ More Information
ROY G BV: red, orange, yellow, green, blue, and violet. All these colors take place in the visible light part of the electromagnetic spectrum. How I put it above, is the exact order it is suppose to go. Red light, has the lowest frequency, and violet has the highest frequency of visible light. THz stands for: Terahertz. nm stands for: Nano meter and it is the SI unit of length and equal to a billionth of a meter.