This is an example page. It differs from posts because it always stays in the same place and (in most themes) is displayed in the website navigation. Most start with an imprint, the privacy policy or an “About us” page to introduce themselves to potential website visitors. For example, it could say:

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, like piña coladas, but less so being left standing in the rain (without an umbrella).

… or something like:

XYZ company was founded in 1971 and has been supplying the public with high-quality products ever since. At its location in a small city, the company employs over 2,000 people and supports the city’s residents 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 website. Have fun!