It's an Internet service located at https://wordpress.com. As a subscriber, you get your own blog. It's free for the basic stuff, or you can become a paid subscriber to access more functionality.
(Key word being service. You don't own a blog, you rent it.)
Right... Look, Facebook's interface looks 10x more confusing than WordPress to me. If I could manage to learn it, someone using Facebook can manage to follow a few step by step guides on WordPress.