How to arrange sub items in two columns in the menu bar

Hi all!

I’d like to arrange sub items in two or more columns, as the sub menu has become too large.
(You have to scroll down in order to see the whole menu).
It’s basically supposed to look like in this Link.

Any clue how to get there with word-press?
Also, a friend told me that it’s not clickable via a smart phone.
So, I would need to click on the icon that starts unfolding the sub menu and then have it stay there unfolded. How do I get there?