This is an example page. It is different from posts because it always stays in the same place and appears (for most themes) in the site navigation. Most start with an imprint, privacy policy or “About Us” page to introduce themselves to potential visitors to the website. For example, there could be:

Hello! During the day I work as a bicycle courier, at night I am an aspiring actor and this is my website. I live in Berlin, have a big dog named Jack, likes Pia Coladas, but less (without umbrella) to be left standing in the rain.

… or something like this:

The company XYZ was founded in 1971 and has been supplying the public with high-quality products ever since. Located in a small city, the company employs more than 2,000 people and supports the city’s inhabitants in many ways.

As a new WordPress user, you should go to your dashboard to delete this page and create new pages and posts for your site. Have fun!