This is a very common question believe it or not. A hen will lay eggs without a cockerel (or to be more accurate a cock since a cockerel is a male under a year of age). In the U.S. cocks are called roosters.
A cock will provide you with fertilised eggs when he has been busy but is not needed for a hen to lay her eggs.
You will not be able to tell the difference between eating fertilised and unfertilised eggs. So unless you are planning to breed from your chickens, you don’t actually need to have a cockerel in order for a chicken to lay eggs.