Nietzsche thinks that music allows us to face the tragedy of human existence, not so much in the sense of a diversion but as a means of "speaking" about life. There are things that can be "said" musically — or perhaps sung — that cannot be said philosophically.
...Since language is always metaphorical — and so never delivers to us the "thing itself" — music is all the more significant. For Nietzsche (like the German Romantics) thinks it has a directness that is unlike language. When Nietzsche contrasts the value to the words of a lyrical poem (and thus the images it conjures up) to the music to which it is set, he makes it clear that music has a revelatory power that language and its images simply cannot have: "Confronted with the supreme revelations of music, we feel, willy-nilly, the crudeness of all imagery and of every emotion that might be adduced by way of an analogy. Thus Beethoven's last quartets put to shame everything visual and the whole realm of empirical reality." So music has a significant edge over words. Of course, whatever it is that music conveys cannot be conveyed by words. So, at a certain point, we are — by definition — unable to "describe" exactly what it is that music says. If it could be put into words, we wouldn't need music.
...Nietzsche is convinced —as were the ancient Greeks — that words sung in rhythm had a special effect upon one that simply was not matched by the bare spoken word.