What is this? A private list of your own characters (main and twinks) - only you can see it. Reach it via "My Characters" in the top menu.
Adding a character Enter name, ruleset, class, specialization and level, optionally mark it as your main character (only one at a time). "Edit" lets you change everything at any time, "Delete" removes an entry.
Armory check "Sync with Armory" compares the entered level with the real Blizzard character: - Green check: level matches. - Yellow warning triangle: level differs - the Armory shows the real, current level. - Red cross: character not found on the Armory (check name and ruleset).
Please note: the Blizzard Armory is not available for WoW: Forever yet, so for now the check will not find your characters. It will start working as soon as Blizzard offers the data - then names, level, race and class can be looked up automatically. That is also why your character's first and last name are required when you register.
Straight to the real character Character names in the list are clickable and open the character's Blizzard Armory page in a new tab (once available).
Note For now the list is purely private and not yet linked to the Raid Calendar or Loot History - that may come in the future.