The document discusses the passive voice and how to transform sentences from active to passive voice. It notes that the passive voice is used when the action is more important than the subject or when the subject is unknown. To form the passive voice, the verb "to be" is used along with the past participle of the main verb. When changing a sentence to the passive voice, the subject becomes the object and is placed after the verb. Examples are provided of changing tenses and inclusion of modal verbs from active to passive voice.