The document discusses indirect speech and how modal verbs are used when changing direct speech to indirect speech. It provides examples of direct speech using modal verbs like "will", "can", "may", "must", and "have to" and shows how they change or "backshift" to "would", "could", "might", "had to", and "had to" respectively when converting to indirect speech. Some modal verbs like "should", "ought to", "would", "could", and "might" do not backshift when used in indirect speech. Perfect modal verbs also do not backshift in indirect speech.