Excel Online is a version of Excel that runs in a web browser. Although it has less functionality than the desktop version, it’s useful if you need to view or make simple changes to an Excel workbook and you happen to be using a computer that doesn’t have Excel on it.
If you (or the company your work for) have a paid-for Office365 account or a free Microsoft account, then you have access to Excel Online.
In March 2018, Microsoft added the ability to create pivot tables in a workbook to Excel Online. In this video I demonstrate how to do it as well as explaining the limitations compared to the Desktop version of Excel