The document provides information and exercises about prepositions in English. It explains that prepositions are short words like "on", "in", and "to" that usually come before nouns or gerund verbs. Even advanced English learners find prepositions difficult since one preposition in their native language may have several translations depending on the situation. The document then gives rules for some commonly used prepositions of time and place and provides exercises for learners to practice using prepositions correctly in contexts like describing pictures, times, transportation, and people's biographies.