My dog knew the reference for dozens of words, maybe north of 100. I spoke to him often and taught him the reference for unique words from the time he was 4 weeks old, when I would mention words he would react in a manner that told me he understood what I was referring to.
For instance, "hey buddy what's on your ear"? He would look at me somewhat puzzled and then turn his head to expose his ear to me.
This is because I taught him what his eye and my eye meant. Same with his ear, his nose, of course his paws etc. Just his body alone he knew a great deal.
He even understood abstractions. Like all dogs, he knew what "walk" meant. He also knew other abstract words as he would respond accordingly.
Sure, he can't speak the language, but like many smart dogs he knew words. If used in a sentence he knew the reference of that specific word.