This symbol describes frequency. It represents the number of times something happens per second. It is measured in Hertz (\( \htmlId{tooltip-u-hertz}{Hz} \)) . This symbol describes frequency. It represents the number of times something happens per second. It is measured in Hertz (\( \htmlId{tooltip-u-hertz}{Hz} \)) . In physics, it might refer to the number of oscillations per second of a light wave. In signal processing, it might refer to how many times a signal oscillates per second.