The document discusses the use of passive voice in sentences. Passive voice is used when the focus is on the action rather than the subject performing the action. It provides examples of active and passive voice sentences. The passive voice can make a statement more polite by leaving out the subject responsible for the action. The document also outlines how to change active voice sentences to passive voice by making the object of the active sentence the subject of the passive sentence and using forms of "to be" plus the past participle of the main verb.