The document discusses the future perfect tense in English. It explains that the future perfect expresses the idea that one action will occur before another in the future or before a specific time. It provides examples of time expressions used with the future perfect, such as "by tomorrow" and "by 9 o'clock." The structure of the future perfect is also explained as subject + will + have + past participle. Sample sentences using the future perfect are given to illustrate its use.