This is your homepage. It's different from a blog post because it will stay in one place and will show up in your site navigation (in most themes).
As a logged in WordPress user, you can edit this page by clicking the Edit Page button in the Toolbar. The page might introduce yourself, or your company, to potential site visitors and say something like this:
Hi there! I'm a bike messenger by day, aspiring actor by night, and this is my website. I live in Los Angeles, have a great dog named Jack, 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 providing quality doohickeys to the public ever since. Located in Gotham City, XYZ employs over 2,000 people and does all kinds of awesome things for the Gotham community.
If you prefer a list of your latest posts to be displayed on your homepage, you should go to your Settings and choose “Your latest posts” as homepage option.