What are the piano pedals for?

There are three pedals that are standard on the piano, I will only address the the that is most widely used:

The DAMPER pedal is often called “the sustain pedal”. This is the pedal most commonly used and the only pedal option when you purchase a keyboard. When you have three pedals, it the pedal furthest to the right.

To know how the damper pedal works, play any key on the piano and let go. Do you hear the note still ringing? Now, press the damper pedal down with your foot, and then play a key on the piano and let go of the key, but don’t let go of the pedal. Do you hear the note still ringing? The answer is yes. When you press the damper pedal while playing the piano, the notes continue to ring for a few moments even after you let go. The sound that keeps ringing is the vibration of the strings inside of the piano. Inside the piano, there is padding called the damnper to keep the strings from vibrating. When you press the damper pedal, all the dampers on the piano are lifted at once, so that every string can vibrate.

This serves two purposes. First, it permits notes to sound connected when fingering can’t make it possible. Second, raising the damper pedal causes all the strings to vibrate with whatever notes are being played, which greatly enriches the tone.
Using the damper “sustain” pedal is fun and easy.  Just use your ear to listen to how it makes your song sound and press and lift where it sounds nice.  Be careful not to overuse or your songs will sound “run together”.