The Electromagnetic Spectrum is a range which scientists use to classify types of Electromagnetic radiation.
Amplitude
Amplitude is how high the wave goes, aka how strong it is.
Frequency
Frequency is how often waves appear.
Wavelength
Wavelength is how far across each wave is, or how wide each one is.
Radio waves have the longest wavelengths, Gamma rays have the shortest wavelengths. Waves with the highest energy have the shortest wavelengths, and longer wavelengths correlate to lower energy. Radio waves, therefore, have the lowest energy of any waves, and Gamma rays have the highest energy of any waves.