Hi,
The number of columns can be applied on "div" and "list", it allow you to set the number of products to display in one row.
For the table layout, you can select the number of columns, it's is dynamically managed depending on the options you enabled, for example the image, the price or name, etc.
The table layout cannot be applied on the categories, if you really need that type of layout for categories, you can select another option and edit the related view in order to have the display you want.
Hope this answer to your questions.