The spectrum over time: frequency from bottom to top, time from left to right, and loudness as brightness. Where two sounds pile up on the same frequency, you see it.
In Sharp mode every frequency is moved to where its energy really is: notes become thin lines, hits sharp edges, and even the lowest octaves are readable.
Lock the spectrogram to Live's bars and it sweeps across the bar like a radar, so the same part of the bar is always in the same place. Or let it scroll by in seconds.