The phrase “butting heads” has two meanings, depending on the context.
One meaning is literal, and it refers to the action of rams or sheep that knock their heads together as a way of fighting or showing dominance. For example, you might say: “The two male rams fiercely butted heads to establish dominance among the group.”
Another meaning is figurative, and it means to disagree or argue with someone strongly or frequently. For example, you might say: “Jonathan and Cynthia always butt heads over politics when they’re together.” or “I got kicked out of the bar when I started butting heads with that guy.”
The phrase “butting heads” is often used as a present participle (ending in -ing) to describe an ongoing situation or action. For example, you might say: “Our boss tries not to schedule Rosie and Mark for the same shifts, since the two often butt heads.” or “They have been butting heads for months over the budget.”