Joomla offers the possibility to display a module just one one or some certain pages, while it is hidden on other page. For example if you want to display your huge header module on the frontpage only, show the "Breadcrumbs" navigation on subpages only etc.
You can do it by assigning your module to the coresponding menu items. For example if your "home" link in your Main Menu is linked to your frontpage and you assign a module just to this menu item, it will appear on your frontpage only.
To assign a module to one, some or all menu items:
1. Login to your Joomla admin backend
2. Go to your Module Manager (click on "extensions->module manager")
3. Select the module you want to assign and hit the "edit" button in the upper right corner
4. Scroll down to the "Menu Assignment" area and make your selection (menu and menu item)
5. Save the changes