Well, then, we can’t offer any suggestions without a link to the site in question, and specifically a link to one of the pages/posts in question. A description of the phrase in question would also be helpful.
The theme absolutely does not generate post or page descriptions on its own. It uses only those values set by the global WordPress Site Title / Description settings, as well as specific page or post titles.
What some plugin might add is beyond the power of a theme to control.