macOS Big Sur (version 11) was released on November 12. This is the latest major Mac operating system update from Apple, after macOS Catalina (version 10.15).
I do NOT recommend running this upgrade right away. I suggest waiting at least until version 11.0.2 or later because I have seen some serious issues with Big Sur. If your Mac is running fine, wait to upgrade. There is no hurry, and I recommend waiting a while on all major OS upgrades anyway because the early releases can tend to be buggy and unstable.
I recently spent several hours working on a client’s Mac that had a failure during the Big Sur upgrade. It completely screwed up his MacBook Pro and we had to wipe the hard drive and start over. I even got an Apple engineer on the phone and they were not very helpful. It was disappointing and, unfortunately, I do not trust early operating system releases from Apple.
Stay on Catalina, or whatever OS version you currently have, until a more stable version of Big Sur is released.
See this Apple article for which Mac models are compatible with Big Sur.
Read more about Big Sur here on the Apple website.