The side panel can be used for both mobile and desktop screens. You can control the visibility of the menu icon via the Styling Options -> Side Panel.
I) Side Panel for Desktop Screens ( > 1024px )
Enable the side panel via Customize > Styling Options > Side Panel.
II) Mobile Menu & Side Panel for Mobile Screens ( <= 1024px )
Mobile menu is a part of the side panel. The Main Navigation menu will be automatically displayed in the side panel in mobile screens. Make sure both “Mobile Side Panel” and “Mobile Menu” options have been checked to display a mobile menu.
III) Custom Mobile Menu
If you want to use a different menu than the Main Navigation, you can create a new menu and assign to the Mobile Navigation location.
IV) Side Panel Widgets
The content of the Side Panel has been divided into 3 widget areas. You can place a widget to be displayed in a desktop or mobile screen( browser window width <= 1024px ) or use the Side Panel (Common) widget location to display your widget in all screen sizes.