The Power Of Music is a side quest you can complete in Chapter 14 of Final Fantasy VII Remake.
This quest can be found in Wall Market, where you'll see the young child Betty walking towards the Jukebox.
She wants you to find music to help motivate people Wall Market. There are three Music Discs to find.
#16 - Good Night, Until Tomorrow
You can find Music Disc #16 - Good Night, Until Tomorrow by talking to a man in the Inn of Wall Market.
#12 - Fight On
You can purchase Music Disc #12 - Fight On from the Souvenir Shop at the Coliseum in Wall Market.
#30 - Stand Up
You can find #30 - Stand Up by talking to a woman in an alleyway near Honeybee Inn.
Once you have found all three, go back to the Jukebox and play each song. Betty will dance to each one, along with a stranger from Wall Market.
Reward: Sharpshooter's Companion Vol. III