Data
From the data tab, you can select the entity and attributes that you want to show on you list view. You have the option of working with the primary entity or any other entity that the one has a relationship with.
Load Default: Will load the default FetchXML that set to the selected CRM entity.
Build: Will let you build the FetchXML, and you will be able to select what fields that you want to display, filter the data, group the data.