A Floating Menu gets automatically created if you assign multiple Floating Action Buttons to one page. You then get one button that opens the other buttons which are dedicated to that page.
So let’s say you want to make a call button only on your mobile pages and multiple other actions on your desktop pages. Then you would get a single click to call floating action button on all your mobile pages and another button on your desktop pages. When you click the button on your desktop pages it will ‘pop’ open the different floating action buttons that you have set up for these pages.