Does it involve attributes, or only skills, feats, spells?
Tav only, or other party members?
Origins?
Companions?
Hirelings?
It involves everything except your race and background. So any skills, feats, attributes, spell slots etc. that came from your class/es, subclass/es and level-ups all get erased when you respec. So if you start out as a wizard and at level 12 you respec into a barbarian you will not have any more spells or spell slots or any of that wizard stuff.
You can also respec companions including origin ones into different classes but that will not change their stories or cinematics where they will still behave and have cinematics for their original class.