WordPress Administrator is a type of user role that has access to all of the administrative features of a WordPress site. Or let say, the first user created during the WordPress installation process is assigned the Administrator role and is called WordPress administrator, which can manage every aspect of the website.
Administrator is the only user role that has the ability to upgrade a WordPress blog. They can change themes and edit core WordPress files by using the built in theme editor, they have access to the WordPress admin area. They also have the ability to add, delete, and modify any plugins on the the site in the same way like disable admin bar for all users.
The admin could modify themes, add new users, add and remove plugins, and administer the site network while the roles of the admin would only be concerned with managing a single site.