Waveform
A picture of sound over time, a line swinging up and down as air pressure changes.
See it in Audio visualizer. Press Microphone, pick Waveform ring and speak: the inner ring is the waveform, bent into a circle.
In plain words
Sound is air pushed back and forth very quickly. A microphone measures that push many thousands of times a second. Drawn as a line over time, the measurements make a waveform. Loud parts swing wide and quiet parts stay near the middle. Editors show waveforms so you can see where words and beats begin.