A newly bought Furby starts out speaking entirely Furbish , the unique language with short words , simple syllables , and various other sounds , that all Furbies use , but are programmed to speak less Furbish as they learn more English as they `` grow '' . Throughout a Furby 's lifetime , it gradually learns English words and phrases , which it begins to speak in place of Furbish . A newly purchased Furby starts out speaking entirely Furbish , the unique language that all Furbies use , but are programmed to speak less Furbish as they gradually start using English .