It's one of the game's "classes". In contrast to other roleplaying games however, they are merely presets that you can alter completely at the start of a new game. In-game, I didn't notice any impact the classes would have.
I left my Inquisitor mostly at his presets except for switching the trait Stench for Pet Pal. So he still is an Inquisitor to me and I roleplay him accordingly: straigthforward, driven and passionate regarding the Source, but also just and fair. My co-op partner also plays her Rogue in line with the class, so the two have interesting conversations and the occational rock-paper-scissors debate.
