Ghost of Tsushima: Resolve
Ghost of Tsushima's Resolve is a resource that accumulates while you are engaged in combat and enables you to heal or to execute special attacks in exchange for consuming it.
Conceptually, it is the measure of a Samurai spirit that lets you push through the pain and injury you sustain.
The circles are built up during combat and can then be used to either heal up or execute devastating attacks. You will have to decide whether you will save them for healing or for landing a deadly move.
Healing with Resolve
The third quick menu item is Healing. You are going to consume Resolve to do this.