That includes posts and pages, WordPress settings, installation and management of plugins and themes, and so on. You need to be logged in to view it, and how much of it you have access to is determined by your user role. Subscribers can only edit their own profile, while administrators can edit everything on the site – content as well as settings.
By default, you can access the administration panel of your website by going to www.domain.com/wp-admin/ (replace domain.com with the domain name for your website).