This is popup preview that you can fill with any content you want.
The plugin include some shortcodes, you can read more about them at the bottom of this page. The main 3 sections to configure the popup are:
Appearance: Where you edit the look and feel of the popup.
Display Rules: Here you choose on which page to display the popup (Set to all by default)
Display options: Some important settings about the plugin, being the more important trigger action.