Here’s the short version…Apple released two patches last night that close security issues in iOS 14 and iPadOS 14. There is at least one report that these security holes “may” have been exploited already, meaning bad actors may be taking advantage of the issue “in the wild.”
We always recommend backing up your devices before applying updates. The simplest method is to confirm you have a recent iCloud backup (Settings > Apple ID (i.e. your name, first button in settings) > iCloud > iCloud back up) and it should tell you when your last successful backup occurred.
Once you’re satisfied with your backup, tap-on-over to run your updates (Settings > General > Software Update) and let the device do its work!
Longer version…the issue stems from the possibility that an application on your device can “elevate privileges” thus granting itself access to data on your device. Not great. Apple has promised more info is coming, but hasn’t offered a lot of detail at this time.