In this video you will learn how to configure the pop-up interactive map feature in ArcGIS online. Pop-ups display descriptive information about collections of common features, also known as feature classes, on a map. The default pop-up will show all the list of attributes associated with the feature layer. Configuring a pop-up allows you to hide or show information that emphasizes the information you want to highlight on your map or project.
ArcGIS Online: How to configure your pop-up windows