Conversation so far:
what are the names of the three pedals on a piano
Modern pianos usually have three pedals, from left to right, the soft pedal, the sostenuto pedal, and the sustaining pedal.
what does the soft piano pedal do
This pedal softens the note and also modifies its tone quality.

Question: what about the sostenuto pedal
Self-contained rewrite: what about the sostenuto piano pedal