Question

what is the wavelength of visible light?

Answer 1

Visible light region is from violet (400 nm) to red (700 nm)
Some sources can give bit different values, but roughly these are the limits.

Answer 2

This "visible light" corresponds to a wavelength range of 400 - 700 nanometers (nm) and a color range of violet through red. The human eye is not capable of "seeing" radiation with wavelengths outside the visible spectrum.