The simple present tense is used to describe habitual or repeated actions, facts that are generally true, and scheduled events in the near future. It expresses ideas such as daily routines, general truths, and transportation timetables. Examples are given such as "I play tennis" to describe a habit, "Cats like milk" as a general fact, and "The train leaves tonight at 6 PM" for a scheduled event. The simple present tense can convey repetition, generalization, or future plans depending on the context.