Every animal species in Zenkora has a language of its own! It uses this language telepathically, so it's not as though every bark or meow is a word (however, it does seem the barking and meowing helps somehow...).
These are called the "secret languages of beasts".
Using this language, animals can communicate with each other much as you and I do. It gets a little trickier once more species enter the mix. When a greyhound attempts to strike up a conversation with a dachshund or a chihuahua, they may find it a little strange at first, but very quickly get used to it. For English speakers, it would be like hearing somebody speak with a strong accent for the first time. But what happens when the species get further and further apart?
Well, it's just a matter of learning and getting used to it. To a dog, speaking to a fox may be difficult (at first), but still way easier than talking to a sparrow. Similarly, a sparrow may find dogs quite frustrating to talk to, but fortunately easier to tell that hawk chasing it to chill out. Whether the hawk listens is, of course, another matter.
But if all animals can use this ability, why can't humans? Well, the truth is, humans would be able to - if humans didn't also develop spoken speech. The act of talking blocks out the ability to hear and use these languages, which makes it way harder - though not impossible - for humans to learn it. On that same note, humans who are raised in the wild by animals will find it just as easy to use the secret languages as their new families.
Now that you know, go ahead and practice. You'll be chatting with your pets in no time!
Just don't try to use your newfound gifts on an Ancient. They'll blow your mind in with a single word. Best to just be polite and back away slowly.