We all know what a dog is. If someone points to a dog and say "perro", you may not know Spanish but you know it is a dog. This is the same with "hund" in German, "cane" in Italian, or "chien" in French. Even if you do not speak a known language and called the dog "barkaloty", you can still convey the meaning that you are talking about the dog.
What property of language allows this?