The document discusses the past continuous tense, including how to form it and examples of its functions. It can be used to express an ongoing or unfinished action at a specific time in the past. It is often used with time expressions like "at 9pm last night" or conjunctions like "when" or "while" to indicate two simultaneous past actions or an interrupted action. Examples are provided to illustrate interrupted actions, parallel actions, and exercises for the reader to practice forming sentences in the past continuous tense.