The Trusted theme has support for page and post excerpts, and it is the hand-crafted page excerpt that is displayed in the area you highlight in your screenshot.
To write an excerpt for any page, go into the page editor and write your own excerpt in the ‘Excerpt’ text area just below the main content area.
If you cannot see anywhere to add an excerpt, click on ‘Screen Options’ tab in the top right and make sure the box next to []Excerpt is checked. Once this box is checked you will be able to see the excerpt area.