In this video, the teacher explains the importance of subject-verb agreement in writing. The teacher provides examples and guides students through identifying subjects and verbs in sentences. Students are given practice exercises to reinforce their understanding of singular and plural subjects and verbs. The teacher also helps students revise sentences to ensure subject-verb agreement, improving the clarity and flow of their writing. The video concludes by encouraging students to apply their knowledge to their own writing and make it more understandable for readers.