Security updates are what help protect your Mac from harmful viruses, spyware, and other malicious software.
But here’s what the end of support means for you: Rest assured that all your Office 2016 apps will continue to function-they won’t disappear from your Mac, nor will you lose any data. “ Support for Office 2016 for Mac will end on October 13, 2020.
(Curiously, it is the same day as the EOL of Office 2010 for Windows.) More about the EOL of Office 2016 for Mac here:
