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:
…or something like this:
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.