Prior to interviewing with BYU's Computer Science Department for a job as a web developer, I hadn't ever heard of Drupal before. I'd used Wordpress, which I thought was decent (if somewhat inflexible), and I'd only heard of Joomla or Mambo in passing. Drupal was a new beast for me.
As soon as I was hired, I had to plunge straight in. I should warn you, I'm a programmer at heart, so I took to Drupal very quickly. There are still some things that flummox me, but I feel that I understand the system.
Drupal, at it's heart, is a content management system. That means that you put it on your site, you install it, and you use it for managing "content". Content can be anything. It can be a blog, a store, a hotel room reservation system, or a set of pages. Or it can be any combination of those. There's really no limit to the sorts of things Drupal can do. All you need is a proper understanding of what you want your site to be able to do and then patience to set it up.
Drupal is built to be flexible. You can add tons of "modules" (thousands if you want), which are small units of code that provide new or different features to your site. Drupal itself is more like a framework that allows all of the modules to interact in a pleasant way. You can also change the layout of your site with a click of a button using "themes."
With these pieces, you can make almost any site imaginable. Some, obviously, would be much more difficult to create than others, and many will require you to write your own module to add some features and functionality you can't find already available. But never fear! Drupal was designed so that this is not only possible, it's quite "easy." (I say easy because I'm a programmer)
Next up is the heart of saving information using Drupal: Content Types.