Subtitles are most commonly used for viewers who can hear the audio, but can’t understand the language spoken.
Subtitles give the audience visual access to the audio content by displaying text of the verbal dialogue on-screen. Subtitles differ from Captions as they don’t include identifying speakers, sound effects, music, and audience reaction.
They usually translate the videos spoken and written language into the viewer’s preferred language. To grasp a better understanding, a subtitle is the text on the screen that is solely dialogue.
i.e. “Get off the road!”