The document discusses the past progressive tense and how it is used to describe actions or states that were ongoing or in progress at a specific time in the past. It provides three examples of the past progressive: 1) to describe an interruption or reinforcement of an action by another action, 2) to provide context about a specific time in the past, and 3) to describe two or more simultaneous actions. The document also includes links to videos and exercises for practicing the past progressive tense.