All waves are characterized by a wavelength and a frequency. The wavelength describes the distance between the crest of each cycle. The frequency is the number of crests that pass any given point every second.
Light is a type of electromagnetic radiation.
Other types of electromagnetic radiation like ultraviolet light, infrared light, radio waves and X-rays also travel in the form of a wave but at wavelengths to which our eyes are insensitive. Sound is not electromagnetic radiation, but sound is a wave as well. Higher pitches are caused by higher frequencies of vibrating molecules that reach your eardrum. Lower pitches are likewise caused by lower frequencies. Explain why the wavelengths just out of the visible spectrum are referred to as ultraviolet and infrared.