This is a sample page. It differs from posts because it always stays in the same place and (with most themes) appears in the navigation bar. Most people start with an "About Us" page with an introduction for possible visitors to the site. For example, it might say there:
Hi! By day I work as a bike courier, by night I'm an aspiring actor and this here is my blog. I live in Berlin, have a big dog named Jack, like Fantastischen Vier and a cold beer.
As a new WordPress user you should use the Dashboard to delete this page and add a new page with your own content instead. Have fun!