For a list of all components and their purpose, please refer to this list of components.
When published, a Call to action block looks like this:
Enter information into the data entry screen for a Call to action component. You'll need a title, some text that describes the call or encourages the visitor to take the action.
You can also add a button that links to a specific URL and some text to display on the button.
There is no individual 'Save' button for a component. Components are saved when you save the page.