[deleted] For a complete newbie who's serious about security, honestly the best recommendation I'd make is to learn more about operating systems in general to understand what some common vulnerabilities are. I realize that's probably not helpful, but you really do have to dig into the details a bit to understand why security-focused operating systems are made the way they are.
As others have mentioned, Qubes is perhaps as good as it gets - especially on proper hardware - while still maintaining reasonable usability. All the primary Linux distros like Debian, Ubuntu, Arch, Fedora and others are (in my opinion) a significant step up from any default Windows OS. That said, Windows can be locked down reasonably well, but it takes some moderate work, judicious install of programs, and tweaks to get there.
Personally today I use Manjaro / Win10 / Win7, all highly tweaked/adjusted with a PFSense dedicated firewall at home.