What does this security breach actually mean--in laymens terms.

It means that a security researcher discovered that people who had purchased and were using the Pegasus spying software could use a vulnerability in iMessage and place software on your iPhone to monitor your activities.

Your phone will only automatically update if you had that option turned on and usually not immediately. If you updated yourself to iOS 14.8 you have closed the vulnerability. Unless you are a head of state, high official in a state, or a journalist working on a major story you didn't have much to worry about with this issue, the Pegasus software is quite expensive.

News reports say this is a no-click vulnerability, that can infect without any action being taken by the user. If I never use iMessage, am I safe, or do I actually need to disable the iMessage app to be safe?

Thanks --

Thanks for (amazingly) quick reply, deggie. Still, it would be helpful to know if I'm at risk -- does disabling or not using iMessage protect me from this no-click malware -- can I safely delay this update until things settle down?

https://www.gottabemobile.com/ios-14-problems-5-things-you-need-to-know/

Just update to iOS 14.8 and you don't have to do either.

As far as anyone knows disabling iMessage will protect you but you would be better off upgrading to iOS 14.8 or waiting until Monday, September 20, 2021 and update to iOS 15.