Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
This problem is most likely caused by the July 13 update, many people are experiencing problems with the Office apps on a Mac after that update..
1
Use the steps provided on this link to remove the Office licence from your Mac.
2
Then, use this process to completely uninstall the Office apps from your Mac.
https://support.microsoft.com/en-us/office/lifecycle/officeinstall/uninstall-office-for-mac
3
Then, go to your Microsoft account on this link to download and reinstall Office.