Category page is the page to show the category information and list of products in that category. Please read the Browsing The Front-end to know how to create the menu item to EShop category page.
In the category page menu item, you should choose a corresponding category from the list to link the menu item to that category.
If you go to EShop -> System -> Configuration -> Layout tab, you will see some configuration options for the category page, they make the category page works flexibly.
You can create multiple category page menu items for your store, each menu item link to a category.