Lyric discussion by Ursza 

Cover art for Nanana lyrics by Kelly Family, The

I think this song is about a (young) man falling in love with a (beautiful) girl; however, the odds are not in their favour ("grey grey world where nobody sings"; "in a place where hell is around the corner"; "if you wanna live you better not touch"): this could hint at a situation close to a civil war - either "small", like Catholics and Protestants in Belfast, or "big" like during the American Civil War, where you could get killed by your own people when they saw you with "the enemy".

Instead to fight for his relationship with the "human doll" he leaves the country ("I left the one that I loved behind"). He returns after some time, only to find out that he cannot get back to the girl. The "Black Swan" could either refer to another man, or - what I think is more likely - it's a symbol for death, meaning the "human doll" has died meanwhile.

The song she sang to him is played in the radio (probably because he turned it into a "suitable" song), and since many people listen to it, she won't be forgotten.

My Interpretation