The document discusses the passive voice and how it is formed by changing the direct complement of the active sentence to the subject of the passive sentence. It provides examples of changing sentences from active to passive voice, such as "Mexicans speak Spanish" becoming "Spanish is spoken by Mexicans" in the passive. The auxillary verb "be" is used in the correct tense and the main verb is changed to the past participle form. The subject of the active sentence becomes the complement of the passive sentence, introduced by "by".