A chicken being "broody" means it wants to be a mother. So she will sit on her eggs or even another chicken's eggs and try to hatch them. This can be good or bad depending if you want chicks or not. When chickens go broody they will sit in their nesting box and lay a few eggs but after a couple of days she will stop laying eggs. It's really easy to know if your chicken is broody or not, if she sits in the nesting box 24/7, yells and hisses, puffs up at anything that moves then your chicken is certainly broody.
If your chicken is broody and you want chicks you need to have a rooster, if there isn't a roster then you cant have chicks. But you can order fertilized eggs online and put them under her and she will be more than happy to hatch them. Your chicken must be very committed to hatching the eggs because she has to sit on the eggs for 21 days! (that's how many days it takes for the eggs to hatch.) My hen April is a gold laced cochin and she is currently broody but our roster doesn't like her, which means her eggs aren't fertilized. Our rooster does like our Cuckoo Marans so I gave her fertilized egg to April. She has been sitting on it for a few days but I don't know if it is going to hatch. Hopefully it will! Check back in about 18 more days and I'll let you know what happens!