The PowerPivot Mode is available with the Enterprise Edition of SQL Server. PowerPivot is still split into two different products: there's a PowerPivot add-on for Excel 2010 and 2013 and PowerPivot for the SharePoint SQL Server component. With Excel 2016, PowerPivot is natively a part of the application. PowerPivot allows Excel to work as a self-service business intelligence, where you can build analytical models with a local analytics engine and use specialized expression language to query data, create measures, and so on.
PowerPivot is also available as a mode for Analysis Services. This mode is used for the SharePoint data access mode on SharePoint 2016 and 2013 farms where you are running PowerPivot workbooks and you require the data access to the data sources.