Breaking News feature allow you to select particular article that will be highlighted on homepage for predefined time.
To open the Breaking News settings click on Sections > Breaking News.
Adjust search criteria if needed and hit Search button. Once you find article you would like to highlight as breaking news add it by green arrow. Set Expiration time from 5 till 60 minutes. After expiration it will be no longer visible on front end site. There is also option to Add Teaser and Add Placeholder which can be any customized message not only article.