The 3-2-1 rule
Three copies of important files, on two different kinds of storage, one of them away from home. In practice: files on the computer, a copy on an external drive and a copy in the cloud. That is enough for a home or a small office.
A cloud copy: OneDrive
Windows 11 has a built-in backup app that saves Documents, Pictures, Desktop and your settings to OneDrive. The free space is small; photos usually need a subscription. The upside is an off-site copy; the downside is that you need internet and access to your account.
An external drive: File History
File History in Control Panel copies your folders to an external drive automatically and keeps older versions of files. Plug the drive in and the copy updates. Any external SSD or HDD works — choose 2–3 times the size of your data.
Check that it restores
A backup you have never restored from is a hope, not a backup. Every few months, open a few files from it. And keep the external drive unplugged when not in use: ransomware damages everything it can reach.