Sometimes "cat" means:
* A gender-nonspecific way to refer to a person and low-key imply that they're cool, e.g. "they are a hip cat"
* A literal feline, e.g. "I have a pet cat"
* A furry, e.g. "this is my cat fursona"
And on the fediverse, it's kind of a roll of the dice which one they mean