So there’s the three pedals on the piano. I rmember that the “sustaining” one moves the felts away from the strings, so the sound lingers much longer than normal.
On a grand piano, the pedals from left to right are usually:
“Soft” pedal, which shifts the whole action slightly to the left or right. This causes the hammers to strike only two of the three strings for most notes.
Sostenuto, which holds up the damper for all notes that were depressed at the time you press the pedal,
Sustain which holds up the damper for all the notes.
Damper — lifts the felt dampers off all the strings, so any notes struck will continue to ring
Una corda — on a grand, shifts the entire hammer assembly to one side, so only one string of the triple-string treble tones, and of the dual-string mezzo notes, gets struck. on an upright or a spinet, shifts the hammer assembly closer, so that the hammer travels less distance and hits the strings with less force. In all cases, it creates a “lighter” sound, hence the nickname “soft pedal”
Sostenuto — This is the pedal that is most often just decorative on pianos-less-than-grand. On a grand, when depressed while a note is being struck, it keeps the damper of the struck strings only suspended; other dampers continue to sit against the strings, including those of other notes subsequently struck (so you have ringing notes with ordinary marcato or stacatto notes possible to you while the other notes continue ringing). On some spinets and uprights, the sostenuto pedal lifts the dampers ever so slightly off the strings but not as much as a damper pedal does, which gives a vague approximation of the effect of a true sostenuto pedal. On some other uprights, the sostenuto pedal works like a second una corda pedal, literally hooked to the very same control rods.
How you use them — you push them down with your feet