The document discusses the use of modal verbs in the English language. It explains that modal verbs are used to express ideas like ability, permission, necessity, obligation, possibility, and probability. Some common modal verbs discussed are can, could, may, might, must, have to, need to, shall, should, will, and would. The document provides examples of how these modal verbs are used in different contexts like expressing ability, permission, obligation, possibility, probability, giving commands or suggestions, and asking questions. It also includes an activity with multiple choice questions to test understanding of using the correct modal verb in different sentences.