From the Super Mario Wiki
Jammin' Toad, or simply Toad, is a Toad wearing headphones, introduced in version 3.0.4 of Super Mario Run. He is found in the Kingdom Builder, and, if tapped on, can play music from the player's music library on their mobile device.
Jammin' Toad gains a more prominent role in Super Mario Odyssey, where he appears in the Sand Kingdom, Wooded Kingdom, Metro Kingdom, Luncheon Kingdom and Mushroom Kingdom after completing the main story. In each of these kingdoms, he requests a certain music piece from the player, sometimes one that relates to an area in the kingdom that the Jammin' Toad is in. The player must find and select the correct piece of music from the in-game Music List, after which the Jammin' Toad will reward Mario with a Power Moon.
If the player fulfills three of Jammin' Toad's requests, "Honeylune Ridge: Escape (8-Bit)" is unlocked in the Music List. Fulfilling all five of Jammin' Toad's requests unlocks the "Music Maestro" Toadette achievement in the Mushroom Kingdom, as well as the song "NDC Festival (8-Bit)", which can be requested to play over the New Donk City Festival instead of the original version of the song.