Hit Singles, like Hit Musicals and Hit Movies and unlike other resources, cannot be obtained by improving a tile. Instead, the owner of the Rock 'n' Roll wonder obtains a certain number based on the map size. Other players must trade with them or conquer the wonder to get it.
As the owner of the Rock 'n' Roll wonder has a monopoly on this resource and controls who does or doesn't have it, it's great for a builder playing the diplomatic game.
Providing AI leaders with resources boosts their relations to you, which helps reduce the risk of war. If they decide to go to war with you anyway, they'll take a happiness hit from losing the resource. The risk of a happiness hit could also help put other players off trying to attack you in multiplayer, though you'd likely need a monopoly on all three resources for it to be significant enough.
As with the other "Hit" resources, Roosevelt is a very good leader to aim for the attached wonders due to America's unique building boosting their effectiveness and Roosevelt being an Industrious leader. Unlike other "Hit" resources, however, Hit Singles also provides a happiness boost to Greece's unique building as well.
Music is an art form that involves audible sound. The sound may be created by human voices, percussion, by hitting or strumming strings under tension, by blowing air across a reed, and so forth. It is impossible to date the origins of music, but instruments made of stone and bone have been discovered dating back more than 45,000 years. Every culture known has developed its own forms of music.
It is impossible to imagine what the earliest forms of music sounded like. It was impossible to record any kind of music until the invention of musical notation. It is believed that ancient Egypt had some form of musical notation dating to 3000 BC, while the Greeks were notating music in 200 BC. The current western style of musical notation is credited to Guido d'Arezzo around 1020 AD.