A brazen head is something people used to make a very long time ago. It was like a fake head made out of special metals and it was quite big, almost like a big pot.
People would put special spells and magic into it to make it really smart. They believed that the brazen head could tell them important things about the future, like who would win a battle or who would be the next king.
But it was just a statue, so it couldn't really talk or think like a real person. People would ask it questions and then they would listen for certain noises, like bells or whistles, to know what the answer was supposed to be.
Even though it wasn't really magic, people believed in it so much that some even thought that the brazen head was alive and had a spirit inside of it. But now we know that it was just an old myth from a long time ago.