What is the meaning of butting?
When sheep or goats want to prove who is the strongest they butt their heads together until one gives up, leaving the other the winner. In the same manner when two people try to dominate each other they may continuosly quarrel in the hope that the other one will yield, this is called "butting heads"
To butt is a verb. Heads is what you're butting. This idiom comes from the fact that sheep and goats and deer fight with their antlers by butting heads. This made people start saying that anyone fighting to see who's the most important person is "butting heads." It implies that they are like rams running to bang their heads together and impress the ewes.