Ten months is when my hens went broody for the first time. I have one right now in "broody treatment" which consists of an open-mesh bottom cage with no bedding with a fan circulating cool air under her. It's her third time broody in the past three months. She's a Cochin. Cochins are broody fiends.
Broodies have a hormone change that makes them crave sitting on a warm, dark nest for a month. They will cackle irritably and puff up like an angry badger when touched. If you want to break a broody, you have to deprive them of the urge by lowering their body temperature, keeping them out in the day light, and air circulating under them. I keep my broodies in a cage inside the run during the day so they can still be with the flock, and at night I bring them into the garage with the fan on their underparts.
This will usually return a broody to normal within three days. If left alone, your broody will sit for a month, lose a lot of weight, not lay any eggs, and in the end, not produce any chicks unless she's been sitting on fertilized eggs.
