That’s the Microsoft Office 365 subscription.
If access to Office documents and Office tools are an requirement and you do not wish a subscription, you can purchase Office 2019 or the upcoming Office 2021 from Microsoft, or can use the LibreOffice package (free), or can use tApple iWork apps (free) (Pages, Numbers, Keynote) to read and write many Office documents.
If this was an upgrade from an older macOS version… There is no uninstall and no downgrade available, your options there are to restore your backups from prior to the upgrade, and you’ll need to revert to Mojave to still have 32-bit apps such as Office 2011 and earlier, and that’ll revert all changes made since the upgrade. Ypumcan install Mojave and Office 2011 if you’d prefer.
If this Mac was first released with Big Sur, then it cannot run earlier versions.