This is a sample page. It is different from posts because it stays in one place and shows up in your site navigation (in most themes). Most people start with an Imprint, Privacy Policy, or an “About Us” page to introduce themselves to potential site visitors. For example, it might say something like this:

Hello! During the day I work as a bike courier, at night I am an aspiring actor, and this is my website. I live in Berlin, have a large dog named Jack, like Piña Coladas, but not being left in the rain (without an umbrella).

… or something like this:

The company XYZ 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 the local community 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!