Floofs are a form of karma on the site. Users who think you're helpful or nice, or just thankful for your contributions might give you nuzzle which in turn lifts your Floof o meter. Once you've made at least 25 posts on the site you'll be given the nuzzle option yourself. You can only nuzzle a user once every 24hrs.
Floof is also a sort of endearing term you'll see used around the community. It's a friendly and sweet nickname some give each other. Nothing more.