Will my Microsoft Office 2011 still work with OS Monterey?

Yes, your documents will continue to be read but not by Office 2011. Office 2011 stopped working with macOS Catalina 10.15 and that’s three versions of macOS ago. If you are running Catalina or later you will need to upgrade your Office and it will not be a free upgrade. Microsoft has moved to a subscription model in which you pay monthly or yearly for Office (now called Microsoft 365). For the time being you can purchase a perpetual license for Office 2019 but Microsoft is doing away with perpetual licenses in 2022 and Microsoft 365 will be subscription only goin forward.

There are free, open source alternatives you might investigate like LibreOffice

https://www.libreoffice.org

Of course Apple’s own suite of products, Pages, Numbers, Keynote can open and save Office documents in Office native format. These are included free.