Windows provides an useful feature that is enabled by default after you install a fresh operating system.
This features create backups for system files (Windows operating system files) such as core libraries and functions.
Is not intended to be a full backup solution for computer, but is good as backup for Windows essential files that may be affected by errors, viruses etc.
If you have restore points created (you can create manually anytime or default ones created automatically by your computer, if you don't turn off this feature), then you can undo or revert your computer to a previous state.
As you can see, i have turned on for disk C: and if i have an error on Windows after i install/uninstall different programs or even i am infected with a virus, i can access System Restore to choose a backup from a previous date.
This feature can be turned off, since will take some hard disk space while creating backups, but is highly recommended to keep it turned on because it may be a very good chance to repair your Windows PC in case of an error or malware.
System Restore is intended to backup important Windows files and installed programs, is not intended to backup another type of files such as personal pictures, Word documents etc.