I've tried to teach my cats some English to make things easier. They recognize their names, each other's names, and the words "out" and "Fancy Feast." They respond appropriately, but that doesn't mean they understand the meaning of those words. When Tommy hears "Tommy," he might think "Oh, that means she's going to pet me." Or when he hears "Apollo," maybe he thinks, "That means she's going to pet the orange cat." Either way works for my purposes.
But parrots actually speak words, and even sentences. Yes, it's mimicry, which many birds are very good at. But what do those words mean to them? Remember the story of Helen Keller in The Miracle Worker. She learned words and which ones to use to get the response she wanted long before she learned that words represent real things in the world. Can parrots learn to understand that? Maybe, if they spend enough time with humans and our language. -via Laughing Squid