The document discusses the two main uses of the present simple tense: 1) To express repeated actions such as habits or schedules, and 2) To express facts or generalizations that are typically true. Some examples are provided such as "I play tennis" to show a habit, and "Cats like milk" to show a generalization. The grammatical rules for forming the present simple are also outlined, including using "s" or "es" for third person singular verbs.