Extra Seats are your coach memberships, that are purchased under a club director or org level membership.
During the purchase of a Club Director membership, directors can opt to purchase extra seats, JVA coach only memberships, at $10 each for their coaches. Directors will then receive a sponsor code, and direct link that they can give to coaches to activate those sponsored memberships.
In the case of an Organizational membership, each level includes a set number of extra seats, with JVA/AVCA coach benefits. Directors will again have the option to purchase additional seats above that, and will receive a sponsor code to have their coaches activate their membership.