The document discusses the present perfect tense in English. It explains that the present perfect is used to talk about actions that happened at an unspecified time before now. It cannot be used with specific time expressions like yesterday or last week. It can be used with unspecific expressions like ever or already. Examples are given of how the present perfect is used to emphasize results, describe ongoing or recent actions, or actions that influence the present. Common signal words used with the present perfect are also listed.