Based on the choices on the fields, Show Price and Show Discount, the relevant fields would be shown in the report.
When both of the check boxes (Show Price and Show Discount) are selected in sale order then it will show Price, Unit-price and Discount in sale order preview and report.
When Show Price is checked then it will show Unit Price and Price in sales order preview and report.
When Show Discount is checked then it will show discount in sales order preview and report.