It's actually supposed to be "HUD", and it means Heads UP Display. All it is is what's on the screen, such as the giant transparent wiimote and nun-chuck in the SS demo.
I thought I heard somewhere that you would have an option to turn it off or on, but either way I'm glad it won't be there. The hearts and rupees don't really bother me, but I did notice that when link got hit a heart would float off his body.