So you have been killing Albs and Mids and your Realm Rank is going higher and higher.  What is so special about that?  Well, actually you get Realm Skill Points per Realm Level you achieve.  These Realm Skill Points can be used at your trainer to purchase Realm Abilities.  Realm Abilities vary per class and there are different types of Realm Abilities.  A list of Realm Abilities, how many Realm Skill Points to buy each Ability and what each Ability does is listed on the Herald [here]