In some cases, you might want to change your column order for mobile devices only.
For example, say you have a 2 column layout with an image on the left and text on the right. On mobile, the image will be on top and the text will be below the image. The Semplice responsive editor offers you the option to change that order.
To do this, enter mobile mode in the responsive editor (small mobile icon at the top of your page) and select the column you want to adjust. Under the 'Column order' option in the editor popup, change the value to change your column order.