Which bird is often taught to talk?

Parrots, and they do it without anything resembling human vocal equipment. A parrot has no vocal cords; sound is produced in the syrinx, a structure at the fork of the windpipe unique to birds, and shaped by an unusually thick and mobile tongue into something a human ear hears as speech.

Whether it means anything became a serious research question rather than a rhetorical one. Alex, an African grey studied for thirty years by Irene Pepperberg, could name colours, shapes and materials, count small quantities, answer which of two objects was larger or the same, and grasp the concept of none - which he appeared to work out himself when asked a question about a set with nothing in it. He was answering novel questions, not reciting.

In the wild the ability is social machinery. Parrots live in large flocks with regional dialects, and there is good evidence that wild parrots give their chicks something equivalent to individual names, which the chicks then use. A bird kept alone treats the household as its flock, which is why it learns the microwave and the phone as readily as words - and why an isolated parrot is a welfare problem rather than an amusing one.