Tenses indicate the timing of actions, categorized into various forms such as simple future, present continuous, past continuous, and perfect tenses. Examples illustrate these concepts: 'He comes to college,' 'She sings,' or variations like 'I will learn' and 'I have learned.' The use of keywords is crucial for understanding tense structures; for instance, using time markers like "since morning" helps clarify duration. Additionally, examples show how different tenses convey completed actions versus ongoing ones—like watching a movie in multiple contexts.