I'm constantly on the lookout for what my animals know, the cats and dog.
They start out knowing nothing about us, our mannerisms, what we say, all that. But then in the course of time they learn all sorts of things, whether to trust us or not.
Somehow they come to associate their name with themselves. I'm still not exactly sure how that happens, except obviously by repetition. But whether they know the names of the others, that's not always clear. I do think our dog knows the words we use for the cats individually.
Then there's all the other things we communicate, especially with the dog. The dog comes in for a lot more interaction because of the bathroom duties. And she, being a dog, cares to be with us more in an intimate and ongoing way than the cats. So she responds to things that are kind, sweet, complimentary, and comes to know things like "Stay" and "No." We think of "sit" as a kind of trick, which is just more of the same.
One thing the cats get trained to respond to, by getting a treat or by having something that will be to their liking, is "Kitty, kitty, kitty" in a high pitched call. You figure they're a blank slate till they get the associations.