A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Please go to the Excel menu and choose About Excel. This displays a dialog showing you the version information. You should have version 14.7.7
If you have any other version, download a fresh copy of the current version of AutoUpdate from this link, install and then run AutoUpdate to bring your installation to current update level, then restart your Mac.
https://go.microsoft.com/fwlink/p/?linkid=830196
If you already have 14.7.7 then restarting your Mac should fix this.