The quality of being quick and lively.
Snappiness is usually a good thing because it means something is full of energy and excitement.
Examples:
The puppy's snappiness makes everyone happy.
I like the snappiness of her dance.
The snappiness of the music makes me want to dance.
The snappiness of the race surprised everyone.
The snappiness of the joke made everyone laugh.
The snappiness of the squirrel's movements was amazing.