Functions of a keyboard

There are three pedals on  a grand piano
1. On the right hands side we have got the Sustaining pedal, this pedal when in use it will lift the Dampers that touch the string in the piano so that they can vibrate longer. This pedal will also make vibrate the string near the note that is being played if the are in range of the frequency this is called sympathetically  vibration

2.In the middle we have got the sostenuto pedal, this pedal will lift the Dampers of the first notes played,sustaining only the notes played when the pedal is actioned, then future notes played won't sound sustained as the Dampers are still hitting the strings.

3. ON the left hand side we have got the Una Corda pedal ( one string ), what this pedal does is to move all the keys to right so that the hammers hit only a single string at the time making the sound of the note softer.