how did the creature learn to speak?

When Safie appears, the creature notes that her language is different from that of the cottagers, and that the four humans have great difficulty in understanding one another. They communicate largely through gesticulation, which the creature is initially unable to interpret; he soon realizes, however, that the cottagers are attempting to teach Safie their language. He secretly takes part in her lessons and, in this way, finally begins to master the art of speech.