Offer Groups section allows assigning the Offer to one of Offer Groups created on HasOffers.
Offer Groups feature allows redirecting users to the most relevant Offer in the group according to their geo-location and devices. For example, you can redirect users who don't speak the same language or use the same device type as the offer they would normally reach.
Offer Groups are only used when the user does not match the targeting rules, so offer that do not have targeting set or do not enforce geotargeting will redirect to the original offer.
If you wish to assign an Offer to the particular group, go to Advanced Settings and select Offer Groups:
Select one or several groups in Selected Groups drop-down menu and click Save:
Read more information about Offer Groups.