Excel Services enables Users to explore data and conduct analysis in a browser window just as they would by using the Excel client.
Excel Services offers certain new features to support business intelligence applications.Like the followings
Data exploration improvements:
People can more easily explore data and conduct analysis in Excel
Services reports that use SQL Server Analysis Services data or PowerPivot data models. Users can also use commands such as Drill Down To to conduct analysis. Users can also apply the Drill Down command by using a single mouse click.
Calculated measures and members:
Excel Services supports calculated measures and calculated members that are created in Excel.
Application BI Servers:
Administrators can specify SQL Server Analysis Services servers to support more advanced analytic capabilities in Excel Services.
Business Intelligence Center update:
The Business Intelligence Center site template has been streamlined. It not only has a new look, it is easier to use.
Excel Services consists of Excel Calculation Services, the Excel Web Access Web Part, and Excel Web Services for programmatic access. It supports sharing, securing, managing, and using Excel 2013 workbooks.
Excel Services is used primarily for business intelligence scenarios. Excel workbooks can be connected to external data sources, reports created, and then the workbook can be published to a SharePoint document library.