The document describes the communicative functions and grammar structure of the present perfect tense. It explains that the present perfect tense is used to describe an event that began in the past and continues in the present or has relevance in the present. It provides examples of the present perfect tense structure using auxiliary verbs like "have" and past participles. It also discusses time expressions that can be used with the present perfect tense to specify duration or limit the timeframe being referred to.