This is called spectrum.

Represents the frequency distribution of the audio signal at the current moment, with low frequency on the left and high frequency on the right.

General playback software uses it as a decoration for music visualization, it just looks good.

A spectrum is a frequency distribution curve. Complex oscillations are decomposed into harmonic oscillations with different amplitudes and frequencies. The pattern in which the amplitudes of these harmonic oscillations are arranged according to frequency is called a spectrum. Widely used in acoustics, optics and radio technology. Spectrum is short for frequency spectral density. It leads the study of signals from the time domain to the frequency domain, thereby bringing a more intuitive understanding.