The document discusses the past tense verb "used to" and how it is used to talk about past habitual or repeated actions. It provides examples of using "used to" with Arnold Schwarzenegger and Luis Aragonés to describe how they were actors and footballers respectively in the past, but have different occupations now. Further examples demonstrate using "used to" to discuss things that existed or situations in the past, like a castle on a hill or living in a village, but are different now. The document encourages thinking of things from one's own past to practice using the phrase.