If you move your head up and down or side to side, you are nodding your head. Up and down means "yes"; side to side means "no."
She’s nodding her head and saying "yes."
He’s nodding his head and saying "no."
Billy’s mother nodded her head no when Billy asked if he could have another popsicle.
When Laurie was asked if she wanted another cup of coffee, she nodded her head and said, "yes."
The students are all nodding their heads after the teacher asked if they would like to leave class five minutes early today.
The two men are nodding their heads in agreement.
The little girl was nodding her head and crying when she saw what happened to her bicycle.
Andy nodded his head and smiled at Jennifer as they passed each other in the hallway. (Nodding one’s head is another way of saying hello or acknowledging the presence of another person.)