Aetherflow & Faerie Gauge
Official Lodestone Job Guide (Always up-to-date)
Aetherflow & Faerie Gauge is Scholar's Job Gauge.
Aetherflow Gauge
Upon learning the action 
Aetherflow, the Aetherflow Gauge will be displayed, indicating stacks of Aetherflow.
Aetherflow can be used to execute certain actions such as 
Lustrate (acquired at level 45) and 
Excogitation (acquired at level 62).
Simple Mode
Faerie Gauge
Upon learning the action 
Aetherpact, you'll be able to view the Faerie Gauge, which displays the amount of fae aether.
Fae aether is accumulated when you use Aetherflow to execute certain actions such as Lustrate or Excogitation during battle while a faerie is summoned. Accumulated fae aether can then be used to perform Aetherpact.
Upon learning the action 
Summon Seraph, you can temporarily call Seraph to fight alongside you in place of Eos. The Faerie Gauge will indicate how much time remains before she must return.
Simple Mode
Normal
Aetherpact Duration
Seraph Duration