Selecting this shows you the current terms and allows you to change the terms of the credit memo. This includes the:
Discount Amount: This is the discount allowed if paid before a certain date.
Discount Date: This is the date up to when the vendor early-payment discount is allowed.
Displayed Terms: This displays the discount, how many days the discount is good for, and the number of days from the date of purchase when payment is due.
If you apply this credit memo to a purchase invoice, the information comes from the purchase invoice.