Reported speech is a way of relaying what someone said without using their exact words. It involves changing verb tenses, pronouns, and other elements to reflect reporting someone's speech indirectly rather than directly quoting them. For example, the direct speech "Sarah said, 'I am going to the movies tonight'" would become the reported speech "Sarah said that she was going to the movies that night." Key aspects of reported speech include changing verb tenses back one tense, adjusting pronouns, and using reporting verbs like "say" or "tell" to introduce the reported information.