A broody hen don’t lay. She has a temperature of 41°C and a bare spot on the chest (brood patch) so that the eggs can be well heated without insulation of the feathers.
The leave of eggs laid togheter is often conducive to the breeding lust.
First the hen continues to sit longer on the nest, then even longer and she makes a clucking sound when she comes from the nest. Against other chickens she takes a defensive stance by keeping the wings spread and erecting the (neck) feathers. She incubates for 21 days.
Please watch that they come once a day from the nest to eat and drink. Otherwise, they can literally brood dead!
Silky Fowl (Gallus gallus domesticus Brisson) are good brooders. You can also put eggs of other fowl under them.

If the eggs are not fertilized brood has obviously no sense. Stopping broody may this way:

• pick her a few days several times a day from the nest until she gives up.
• close the nest box again after all the chickens have laid. Take often away all eggs.
• wet the rear of the hen with cold water so that the body temperature drops.
• Or, easier, and also works in refractory cases: just lock in the hen about 4 days with food and water, without litter. Can also under a crate.

Stimulating broodiness can be done by placing artificial eggs into nests, or letting eggs accumulate in a rather dark place near the floor, and keeping the hen warm. Showing chicks can induce broodiness.