Menu Stacks provide Dropdown and Vertical menus that you can place on your page, whether or not your theme comes with one.
With Menu Stacks, you can control what you want to show in your menus. You can show menus that are: - independent of your site structure/pages. This means you can create menus that are different in structure from your site, for example. You can use these on any themes. - dynamically generated from your site pages. This means that you can use it on the FreeStack theme, meaning more choices on the kinds of navigational menus that you can use on the FreeStack theme.