The methods in controllers are called
actions, but they can have any name. In your case, you specify in the routes that the
/about route will map to the
PagesController and the
about action. Therefore your controller should look like this:
class PagesController < ApplicationController
Since having an empty action in the controller does not add much, Rails is intelligent enough to render the about page from the views if you have one. I would not advise you to take advantage of this to often as it may lead to some confusion. Prefer to explicitly define all the actions in the controller.
Hope it helps.