Yes, you have guessed it right. I am going to talk about a distribution of Gnu/Linux, or Linux. *
Linux Mint is an easy operating system, in the matter of user-friendliness. You do not need to think whether you would need to install X or Y, you can run the operating system right after installation. Of course, if you want to install a package, you can easily do that through the software manager. There you can browse multiple programs, called “packages”, such as games, web browsers and image editors to name a few.
It is completely without fee (if you download the .iso package), and the only thing that you would need would be either a CD/DVD disc or usb stick that can hold the size of the .iso file. It should work directly out-of-the-box, but if you would need some extra packages (that could not be included due to legal reasons) just install them easily through the software manager.
Remember, if you install this on your computer, all your files on your hard drive will be removed. This is true, if you install it onto the whole hard drive. So remember to make a backup of your hard drive if something would go wrong or if you would regret installing it.