Oh, you know - set the scene, narrate the action, deliver character motivations and stuff like that as necessary. It's very much -

Once upon a time!

[He spreads his hands precisely in time with the opening chords, as if he's cuing it.]

In a far-off kingdom
Lived a young maiden,
A sad young lad,
And a childless baker - with his wife.

[And he waves a hand again to cut off the music.]

I don't do it quite so much like a storybook - wouldn't really be appropriate. People get that version, though.