This menu item type creates a menu placeholder, or Text Separator, within a menu and is used to break up a long menu. From the Menu Item Manager, select the New icon from the toolbar to make a blank separator. When you select the New icon, you’ll see a screen to select the menu item type. On this screen, select Text Separator from the Menu Item Type combo box. That’s it; you don’t need to enter any information—just click the Save & Close icon to save this separator in the form of a blank line.
To see the effect of this separator, you can add one more menu item after this separator. Make a menu item of any type and save it. You should now have two menu items with a separator in between. When you open the browser window to open the Joomla web site, you’ll find that the two menu items are displayed with a Text Separator in between.
Source: Harwani B M (2015), Foundations of Joomla!, Apress; 2nd ed edition