After the administrator, the editor has the most powerful role. This role is meant for those users who need to manage everything about the content of a website, but who don't need to be able to change the basic structure, design, or functionality of the website itself (that's for administrators).
To get an idea of what the screen looks like when a user logs in as an editor, let's take a look at the editor's menu (on the right) in comparison to the administrator's menu (on the left):
As you can see, the top section is unchanged (apart from the Updates link). However, nearly the entire bottom menu, with Appearance, Plugins, Users (which is replaced with Profile), and Settings, has disappeared. We can see that the editor is left with only the ability to edit their own profile and to access the Tools section, which includes any plugin pages that allow editor-level users.
The examples of actions that a user with the editor role can perform are as follows:
- Manage all posts
- Create and edit pages
- Moderate comments
- Manage categories, tags, and links
- Edit other users' content
There's one advantageous aspect of the editor's role. If you take a closer look, you'll see that it has all the credentials that you would need to publish any piece of content on a given WordPress site. This makes it perfect for everyday use, even for single-author blogs/sites. Therefore, what I actually encourage you to do is set a separate editor account for yourself, and then use it for posting and editing content, instead of working with the default administrator account. This setup is a lot safer, particularly if someone tries to hijack your password, or in the event of any other mishap to your account, the site itself won't get harmed (because editors can't install new plugins or delete any existing ones).
For multi-author blogs/sites, the editor role is meant to be assigned to users who are in charge of the content published on the site. As the name itself indicates, the editor role is perfect for editors.