I am guessing she means that Kit is organized and punctual, that she takes care of things like figuring out Zoom and paying for the pro membership, that she is careful not to express her emotions if she thinks they might be too "messy," that she responds calmly (at least on the outside) to cancelations and session disruptions, etc. She is an "easy" client, even if she really deserves much more space to express herself. I think that's what her T meant.