Microsoft Office (Word, Excel, PowerPoint, Access) is a separate program and needs to be purchased from Microsoft. One free option (which I use) is LibreOffice which includes Calc (an Excel clone) and is compatible with MS Office .xls files.
From what I can tell from searching online is that when new, the ES15 shipped with a 1 month trial version of office from most vendors. Some vendors offer it with MS Office, but it must be specified at time of purchase and would cost more. Here is the Amazon link that I could find: