>>127278896
a compressor reduces the dynamic range of your signal.
the threshold knob says "anything above this line gonna get pushed down"

the ratio is all "im gonna push you down this hard, get under the threshold, kid"

the level or output will say "aww, cute little quiet notes, put on these platform shoes so you seem taller"

some compressors will have a speed knob too, fast speed means the level is basically capped at a certain point and slow speed will mean it takes a second to kick in on loud notes so you can still have clear picking but held notes will be tamed