A Mega Menu is an extension to your site menu, which will display a large panel of content below a menu item when the user clicks or hovers over the menu item. A mega menu provides a great user interface when you have many sub-menu items, as it will reveal all lower-level pages at a glance.
To change your site to use a Mega Menu, click the pencil icon displayed to the right of your menu.
Select Menu Style.
Check on Display Mega Menu. The content bar displaying the sub menu pages will inherit the Hover Colour and the Text Colour set for your menu.
You can further customise your Mega Menu by adding an image to the sub menu bar. Hover over the main menu item to invoke the Mega Menu, then click +Add Image. Select an image, then click Save.