You can count a fraction of something.
My daughter picked up the habit of saying “0”, then “1”. (I think she got it from school.)
I was surprised, but I think it’s a good habit for a kid to adopt.
It’ll probably help when she’s formally introduced to concepts like fractions & integers. There’s something between “0” and “1”.
You may be able to calculate a fraction of something. However calculation any fraction of zero is impossible. For there is nothing that can be divided up into smaller parts when there is nothing which exists in the first place.