Hopefully this will help someone. It took me a while to realise how to set this up.

To get only the categories to show on the fronpage you have to create a top category (ie. "Home") that will contain all the categories you want to show on the frontpage.
Then you will have to set ALL the items to "0" (zero) in the "Category item layout" tab.
Proceed to the "Category view options" and set the "Sub-category blocks" to "Show".

Now, go to the Menus and change the "Home" (default) link to a "K2 category list" menu item and set it to only show the top category.

If you check the frontpage of your website now you should be able to see your new, polished K2 category list frontpage!

first i wanna say thnx for you i make ur SOLUTION and it is work with me
but i have question whey when i click on a item from the frontpage to read more it is show me the item but with the other items on the next page ???
why????
thnx