Light is one form of radiation. Radio waves, X-rays, color, and heat are all expressions of radiation. The wavelength is the distance between sucessive peaks and frequency is the number of wave passing a given point in a fixed amount of time. Wavelength and frequency are inversely related. Radiation can also be described as Energy.
Photons have a set amount of energy - the energy is quantized.
As frequency increases so does energy. Radiation with high energy has a high frequency. High frequency means short wavelength. Visible light makes up only a tiny portion of all of the electromagnetic spectrum. Refer to Figure 2.2 in your text and be able to reference the other types of radiation relative to visible light with respect to energy, frequency and wavelength.