a device that displays words for people to read

Presentation prompting service, the script is typed onto a continuous roll of paper which is transmitted to a TV monitor housed at the base of the speaker's lectern.

a system of mirrors and lenses which displays a newsreader’s script as a superimposed moving image on the camera lens, so the reader doesn’t have to look down (much) while reading. Various trademarked names, including the old TelePrompTer.