In Automator actions and variables are contained in the Library. In the Automator window, switch between them by clicking either Actions or Variables. The items are grouped into functional categories in the Library column. The actions and variables themselves are displayed in the second column.
Automator comes with hundreds of actions, and dozens of standard variables preloaded in the Library. When you install an app that includes its own actions, frequently the actions are automatically added into the Library. You can also import new actions into the Library.