This shows when you have a movement-impairing effect that also applies a DoT or other negative effect that you can remove yourself with a freedom ability. It shows both the icon of the debuff and also your options to remove it.
Currently supported are:
Hunter
Posthaste (talent)
Master's Call (pet ability)
Druid
Shapeshift
Paladin
Blessing of Freedom
Monk
Tiger's Lust
Invoke Chi-Ji, the Red Crane
Death Knight
Death's Advance
Wraith Walk
Priest
Dispersion
Phantasm (talent)
Rogue
Vanish
Shaman
Spiritwalk
Thunderous Paws (talent)
Mage
Ice Block (may remove)
Warlock
Demonic Circle
Dark Pact
Gnome
Escape Artist