There is more than one way to tell a story. Sometimes the narrator of a story summarizes what other characters say. We call this style of speech, reported speech or indirect speech. It looks like this:

The President said that NAFTA would eventually be a boon to small businesses in both countries.
Professor Villa told her students the textbooks were not yet in the bookstore.

The opposite of reported speech is direct speech, where you need quotation marks. Such as: 

The President said, "NAFTA will eventually be a boon to small businesses in both countries."
Professor Villa said, "Students, the textbooks are not yet in the bookstore."

Interestingly reported speech is often a tool found in direct narration, where we, as readers, are told what to think of events and how they unfolded.