This left-most HTML table column in the custom columns settings table has no input. Instead, it is used to sort (drag and drop) the order of the HTML table rows (hence the custom columns) as you wish. To perform a sort, hover your mouse on a row in this HTML table column, hold and drag it to your desired location. In your InputfieldVariations inputfield, your custom columns will be displayed in the order you set here (but after the pre-defined attribute options for a given variation).
In the next section, we look at how to use Variations. We will show you how to create attributes, generate variations and link them to a page, as well as how to edit the values for the custom columns you created when setting up the field.