This is a sample page. It differs from posts in that it always stays in the same place and (with most themes) appears in the site navigation. Most start with an imprint, privacy policy, or "About Us" page to introduce themselves to potential site visitors. It might say there, for example:

Hi! By day I work as a bike courier, by night I'm an aspiring actor and this here is my website. I live in Berlin, have a big dog named Jack, like Pi├▒a Coladas but less being left out in the rain (without an umbrella).

...or something like this:

XYZ Company was founded in 1971 and has been providing the public with high-quality products ever since. At its location in a small metropolitan 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 website. Have fun!