Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
1
Press Ctrl while you are opening Word, to open Word in Safe Mode, does Word open correctly?
2
If not, the best option is to perform a full repair of your Office installation.
Open the Settings App (gear icon on your Start Menu)
Go to Apps - Installed Apps, then scroll down to find Microsoft Office
Select that and choose Modify - Online Repair
That should fix any issues with your Office Installation.
3
If that does not resolve the problem, completely uninstall Office, then restart (not shut down) your PC.
Then go to your account on this link and from there, download and completely re-install Office.