The Onscreen Shortcut button is an assignable shortcut for one-touch access to important Security-related features. The Onscreen Shortcut button appears over the home screen and certain other menus.

Assign the feature at  Settings > Onscreen Shortcut:  

When assigned, the button you've selected is superimposed on the lower right corner of the screen:

  

Please note that the availability of the Keypad shortcut varies with the type of control panel running your system.