It looks a bit like a tumor, especially if it feels firm, but it also could be swelling from a sinus infection or an abscess from a peck wound. The later two should feel softer. Does she have any sneezing, nasal drainage, or other respiratory symptoms?
No she doesn't have any of those symptoms that I know of. It is a little squishy not much though. My uncle raises chickens and recommended my using a syringe to try and drain it and then apply an antibotic rub. I haven't tried it yet.
Definitely isolate her from the rest of the flock. It might be the start of a respiratory disease, some quite nasty for a flock, but it is a good sign that she does not have runny eyes/nose or sneezing/coughing.
I'd probably try some warm heat packs with black tea bags to see if that helps make it softer. It might be swelling from an infected sinus which can come from fungal or bacterial.
This is a bit of watch and wait to see if it will drain on its own or is a precursor of illness. If it gets softer and looks like local infection, I'd put her on some antibiotics and possibly do as your friend suggests in aspirating it.