Marketing tool
Admin->Addons->Announcements
Allow shop owners to set a pop up window with an announcement. It will be shown to any website visitor only once in 24 hours period does not matter what page was loaded.
Example: You wish to let all new comers know in an "aggressive way" that you have 10% discount if they buy products over $100.
Full details (manual) here
https://youtu.be/ZgJ-M2GFT18?list=PLmjNeQ4k1bU-tjiRVzvClyWc7mjYAYzSt