The Shelf Layout Sheet is used to specify the Shelf layout and where the products are placed on a shelf. Please see the video to explain further this sheet and how to fill it in: As always, you can download this template from the SharePoint template folder here.
Also, if you are having issues with SKUs not matching, best to checkout this video here on how to use the simple excel formula to check the product data sheet against the layout sheet. and vis versa SKU Error Matching in excel