Naufragare means "to be shipwrecked" or "to be lost at sea." It's a dramatic and evocative verb that paints a vivid picture of being completely overwhelmed or adrift.
In the song, the lyrics
Sal Da Vinci sings "Poesia" to a woman he cannot describe any other way. She is not like poetry to him, she simply is poetry. She stays poetic even when she gets things wrong, she talks about the sea and about shipwrecks, she brings up love on the way down a staircase, and she can fold the whole meaning of life into a single line.
The chorus is about permanence. Everything else rushes past, but she stays. She moves through every street, she never lies, and she lives somewhere between beauty and madness. The song then lands on the line it is built around: she is poetry that has no need of a melody, which is a generous thing for a singer to say.
Two lines slip out of standard Italian and into Neapolitan, the dialect of Da Vinci's own city. "Tu rimani pe' l'eternita" uses "pe'" where standard Italian uses "per", and "Si fuss 'na canzone" is Neapolitan for "se fossi una canzone", meaning "if you were a song". The rest of the lyric is standard Italian, so these are a small taste of Naples rather than a barrier.