The quality of being lively, cheerful, and full of energy.
Sprightfulness is usually seen as a positive and happy quality.
Examples:
Her sprightfulness brightened up the room.
I love her sprightfulness in the morning.
The puppy's sprightfulness is contagious.
His sprightfulness is like sunshine on a rainy day.
The sprightfulness of the children was like a burst of fireworks.
The sprightfulness of the music made everyone want to dance.