It's just text to speech.
It uses the google's tts service.
So it needs to be connected on the internet.
■ It provides 38 languages
Afrikaans, Albanian, Arabic, Catalan, Chinese Simplified, Chinese Traditional, Croatian, Czech, Danish, Dutch, English, Finnish, French, German, Greek, Hindi, Hungarian, Icelandic, Indonesian, Italian, Japanese, Korean, Latvian, Macedonian, Norwegian, Polish, Portuguese, Romanian, Russian, Serbian, Slovak, Spanish, Swahili, Swedish, Thai, Turkish, Vietnamese, Welsh.