As the name suggests, the Live Captions feature provides real-time captioning for the audio and video played on your device – except phone and video calls.
Live Captions work even without an active Internet connection and all the processing is done on-device, so the captions remain private.
Android (@Android) December 3, 2019
This feature should be useful in situations where you are unable to hear the audio because of noisy surroundings and don’t have your earphones handy. But, it would be more useful to the people who are deaf and hard of hearing.
Live Captions currently only support English, but Google plans to add more languages in the future and it’s also working with Android device manufacturers for wider availability of Live Captions.