Menu navigation group is the science and skill which you apply to a web site that helps visitors move from one page to another. In short Menu group is a collection of numbers of menus assembled together that helps visitors move from one page to another through a synchronized line bar like below :
How to create a new Menu Group ? To create new Menu Group log on to ADMIN => Menu => Create New Menu Group which will take you to the following page. Type a new menu group name and save it.