Every Mac user should be backing up the files on their Mac. The easiest way to do this is to use Time Machine, which is part of macOS. You can get a cheap external hard drive and start doing this today. Time Machine is simple and automatic and can save you from disasters, as long as you start using it.
If you aren't using Time Machine to back up your Mac, then it is time to start. Here are some options for a Time Machine backup drive.