"У неё меньше кошек, и это хорошо."
Translation:She has fewer cats and that is good.
Nice try, and you could be right, but Yandex translated that as "she has less cats".
Amusingly, Google translated your sentence as "she has less cat". Although that logically follows from our intended meaning, I think something has been lost. ))) Be careful with translation software.
·большой - large, big
·больше - more, larger, bigger
·побольше - larger, bigger
·маленький - small
·меньше - less, smaller, tinier
·поменьше - smaller, tinier
I hope this helps!