An XML file contains a list of data objects you use on a Web page or to transfer data from one database system to another. To open the XML file, you can use a third-party custom application for ...

Simply put, .xlsx is a file extension for the open XML spreadsheet used by Microsoft Excel from 2007 onwards. Why the change in format from earlier versions of Excel?

To be able to import your data into Excel, you must export the PDF as an XML file using Adobe Acrobat 9 Pro Extended. Excel can open XML files and create fully functional spreadsheets out of them.