After language selection, the user has to select the installation profile of the website. You can read more about the installation profile here. In simple terms, the installation profile bundles up the features and configuration in such a way that you don't have to start from zero when setting up a website. When we pick a particular installation it automatically enables those features and configurations which were packaged in it. Drupal core provides a few installation profiles and we also have many contributed installation profiles (Can be referred as distributions sometimes).
I selected the "Standard" installation profile for now, since i am about to explore all the important features of Drupal. You can experiment by picking up "Minimal" which will only limited features enabled or you can go with "Umami" which will setup a sample Food blog magazine to demonstrate capablities of Drupal.