If someone is bull-headed, they have already decided what they want and they push on, without stopping to listen or to think whether the idea is any good. It is not a compliment. The picture is a bull putting its head down and charging. The word is informal, a little old-fashioned in some places, and close to stubborn or pig-headed. You use it about people and their plans, not about the shape of a real bull’s head.

頑固的、牛脾氣的（不聽勸、橫衝直撞）