What does a fortune teller mean by a flat head?

What does a flat head mean in fortune telling?

In the eight-character theory, it is useful to talk about good or bad luck with flat head, defection and hanging needles. This is a font based on heavenly stems and earthly branches, for example; C, Unitary is flat head, E is defense, Ding Wu is garter, etc. I don't know whether it's fierce or lucky. Sometimes there must be something in life, so let it be.