I checked just for the BE, IT, NL websites.
In any case:
Up to 10% off Purchase period: 19 to 26 December
Valid only for routes operated by Iberia Operadora, Iberia Express and Iberia Regional Air Nostrum.
Valid for one year, both to buy tickets and take your flight.
They are not compatible with other promotions or discounts, and they are not valid for joint purchases of flight+hotel or flight+car.
They cannot be combined.
They are non-refundable.
it works also on custom amount (2000 eur gift card = 1800 eur to pay)
https://www.iberia.com/BE/gift-card/