Spectrum relates to the radio frequencies allocated to the mobile industry and other sectors for communication over the airwaves. Because the mobile industry has demonstrated — time and time again — its potential to generate economic value and social benefit, operators are urging national regulators to release sufficient, affordable spectrum in a timely manner for mobile. Additional spectrum, including both coverage and capacity bands, means mobile operators can connect more people and offer faster speeds.
If you want to learn more about mobile spectrum, the GSMA has produced a set of handbooks that offer introductions to spectrum and spectrum management. The handbooks plus a dictionary can be found here.