The module is ideal for very complex nested menu items.
Before we get into it, you’ll need to understand the difference between the Menu and Menu items in Joomla.
Joomla’s default implementation with sample data comes with some menu items that you can rename and use as your own. If you want a multi-level menu item, you will need to have categories in place with associated articles. And, of course, you will need a parent menu. Then you can create a sub-menu to which you can associate the categorized articles.
To add the menu items, follow these steps:
1. Go to Main Menu > Add New Menu item
The process is the same regardless of what style of menu you’re using.
2. For each new menu item, you’ll need to fill out the following fields in the Details tab - the other fields are optional.
Then press Save.
Go to Content > Site Modules and find the Accordion menu module. This module isn't automatically shown on the site's front-end and you need to enable it. Subsequently, you can select where the module should appear on the site, by choosing one of the available Module Positions of the active Template. Don't forget to select a menu you want the module to display it.