A feature is programming set up on a website to input and display certain types of content. These types of content are built as features to make it easier and more efficient for you to add and edit these particular types of content.
For example, when you have a news feature, it allows you to add a news post just once, and the website programming will automatically make it appear everywhere news posts are displayed (i.e. on the news page and on the news teaser block on the home page).
If these features are enabled on your site, you will see them as an option when you select Content > Add content from the Admin menu. If you don't see them as an option, and would like to have them enabled, please email firstname.lastname@example.org.
If you are editing content on your site and find that there is no "edit" tab, it is probably a custom content type or feature.