This is an instance page. It’s different from a blog post because it will stay in one place and will emerge in your site navigation (in most themes). Most people start with an About page that presents them to potential website visitors. It might say something like this:
Hello there! I’m a bike messenger by day, aspiring actor by night, and this is my site. I live in Los Angeles, have a superb mutt named Wank, and I like piña coladas. (And gettin’ caught in the rain.)
…or something like this:
The XYZ Doohickey Company was founded in 1971, and has been giving quality doohickeys to the public ever since. Located in Gotham City, XYZ employs over TWO,000 people and does all kinds of astounding things for the Gotham community.
As a fresh WordPress user, you should go to your dashboard to delete this page and create new pages for your content. Play!