The phrase "few handfuls" means a small amount that you can hold in your hand. It refers to a quantity that is not very large or significant. Full definition
I added few handful of fresh basil leaves which may not be very authentic but I could not resist the fresh produce from our own kitchen garden. (flavorquotient.com)
A good few handfuls of Pomegranate seeds and a sprinkling of crunchy sunflower and flaxseeds over everything to finish off with a flourish. (nutritiousdeliciousness.com)
I have seen the reaction of the few handfuls of people who have tested Babl so far, and many of them have found it addictive. (businessinsider.com)