Hotel Transylvania (Meaning of my Zing)

"You are my 'zing'" means that Jonny is Mavis's love, and vice versa. That means that they are in love, and they have that "spark". I thought it was a cute movie, but a little odd that they referred the word "zing" to love. But yeah, they refer it to mean love, only because the movie was aimed for younger kids, and wouldn't understand love yet, so they used the word zing instead of love.