Articles are comprised of a number of elements: the title, the top title, the subtitle, the description, the deck (or standfirst), the postscript... However, some sites do not need all these elements: either the editors do not use them or the graphical layout of the public site does not include them.
In order to make the site’s management interface less cluttered and/or simply to stop the editors from using certain elements that the webmaster does not wish to include, "The site’s content" configuration page allows you to completely disable the use of any of these elements.
N.B. It is important to understand that, with regard to the choice of simplified interface / complete interface, which only influences the interface of each user, the choice of the options of "The site’s content" configuration page affects all of the site’s users. So if you disable the use of the top title, none of the editors nor the administrators can use top titles in their articles.
The backend interface will also adapt to the presence or the absence of these elements. If you disable the use of keywords, the corresponding button in the top navigation bar will simply disappear.