Cloning, as it applies to fix hacked wordpress, is the act of creating an exact replica of your WordPress install. What is good is that in only a couple clicks, you can do it with the correct software. There are a lot of reasons why you may want to do this. Here are only a few.
There are many ways to pull this off, and many involve copying and FTPing files, exporting and re-establishing databases and more. Some of them are very complex, so it's imperative that you select the one that is right. If you're not of the persuasion that is technical, then you may want to check into using a plugin for WordPress backups.
Yes, you need to do regular backups of your website. I recommend at least a weekly database backup and a monthly "full" backup. More. If you make frequent additions and additional resources changes definitely more. If you make changes multiple times every day, or have a community of people which are in there all the time, a backup should be a minimum.
As I (our fictitious Joe the Hacker) understand, people have far too many usernames and passwords to remember. You have got Twitter, Facebook, your online banking, LinkedIn, two Continued site logins, FTP, internet hosting, etc. accounts which all come with logins and passwords you will need to remember.
Do your homework and some hunting, but if you're pressed for time and need to get this try out the WordPress safety plugin that I use. It is a relief to know that my website (and company!) are secure.