You do not need expensive software or a computing degree to keep a computer reasonably safe. Most infections come down to a few habits, and getting those right stops the vast majority of trouble.
Most malware sneaks in through holes that an update has already fixed. Letting Windows or macOS update itself, and keeping your browser current, closes those holes.
The most common way computers get infected is a person clicking something they should not, a dodgy email attachment, a fake download button, a "you have won" pop-up. If it looks off, it probably is.
Windows has solid built-in protection these days. Leaving it turned on and up to date is enough for most people, without paying for a bloated third-party suite.
Ransomware locks your files and demands payment. A recent backup makes that threat far less frightening, because you can simply restore and move on.
A password manager means one breach does not expose every account you own. Add two-factor login on your email and banking.
If something has already got in, we clean it out properly and set up protection so it does not happen again. See virus and spyware removal.