These are the various icons you'll see in your Unit Status circle throughout the game. Enthusiastic is the best one and you'd like to work towards / stay in that status as much as you can.

Icon Name Description
Unitstatus-energetic Enthusiastic All three unit members are getting along well and morale is high; all are showing an extraordinary level of energy.
Unitstatus-dancing Dancing Someone in the unit is focusing on Dance. If you do a dance lesson, then...
Sparkling Someone in the unit is focusing on Visuals. If you do a visual lesson, then...
Unitstatus-humming Humming Someone in the unit is focusing on Vocals. If you do a vocal lesson, then...
Unitstatus-normal Normal Good balance is being maintained. All girls show a normal level of energy.
Unitstatus-sweatdrop The Showoff One girl is gung-ho about the unit while the remaining two are feeling left out. The enthusiastic girl stands out with her high level of energy for work.
Unitstatus-heartbreak The Sulker Two of the girls in your unit are getting along while one is feeling left out of the clique. The two that are friendly will have a higher energy level for work.
Unitstatus-infighting In-Fighting Two of the girls in your unit are having a fight. They won't be interested in putting much energy into work. The girl caught in the middle might find it difficult to behave for long.
"..." Fatigued One of your girls is feeling exhausted. The tired-out one won't be able to muster much energy for work.
"zzz" Burned-Out More than fatigued, one of your girls is feeling completely burned out. If things continue as they are, the stress will become dangerous to her health and she'll be unable to work.
Unitstatus-demoralized Demoralized All three girls have low morale. None of them will be able to muster any energy for work.

The game manual doesn't specify what should happen if you're in Humming status and do a vocal lesson (for example). It stands to reason that doing so might be another thing that could give a bump up to your danketsu power in addition to the lesson stat boost.

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