The document discusses the present simple negative form in English. It explains that to make a sentence negative in the 3rd person singular (he, she, it), we use the auxiliary verb "does" instead of "s" at the end of the infinitive verb. It provides an example of changing the positive sentence "A teacher works in a school" into the negative version "A teacher doesn't work in a restaurant" using the structure of subject + auxiliary verb (not) + verb infinitive.