First of all you should always attach a .twbx file so that your data also comes with your workbook.
For the labels, just create a calculated field saying sum(sales)-sum(profit). Drag it to the Text mark. Tableau will display it. Then after you can either use the alignment option within the Text mark to align the labels as per desired or you can even manually align them. Just click on any bar and then hover over the label value and you will be able to align it manually.