Rows 1 - 3 are their premium economy cabin. They look similar (identical?) to Iberia's A350 premium economy seats. They charge a large premium over the regular economy seats for them and they still make you pay 45E - 75E to select seats. I did see a sign at the check in counter that read "upgrade to premium" for $199. I didn't inquire but that might be a better deal. I didn't check out the seats but my experience with Iberia A350 premium economy was very positive.

Rows 4 - 6 are regular economy mini cabin. If the flight is full, those are probably the best economy class section. I didn't check how full it was on my flight. You can select those seats for 40E to 75E (bulkhead, they call it XL Seats). Those rows will probably get assigned the last on a fuller flight.