This is an example page. It's different from posts because it stays in the same place and (on most themes) appears in the site navigation. Most start with a legal notice, privacy policy or an “About Us” page to introduce themselves to potential website visitors. For example, it could say:
Hello! By day I work as a bike courier, by night I'm an aspiring actor and this is my website. I live in Berlin, have a big dog named Jack, like piña coladas, but less of being left out in the rain (without an umbrella).
… or something like:
XYZ Company was founded in 1971 and has been providing the public with high quality products ever since. Located in a small city, the company employs over 2,000 people and supports city residents in many ways.
As a new WordPress user, you should your dashboard to delete this page and create new pages and posts for your site. Have fun!