The phrase "What's your beef?" is an informal slang expression that means "What is your problem?", "What are you complaining about?", or "Why are you upset?".When someone asks you this, they are noticing that you seem annoyed, hostile, or dissatisfied with a specific person, situation, or rule, and they want to know the reason behind your grievance.Key Meanings of "Beef" in SlangTo have a beef / to have beef: To have an ongoing conflict, grudge, or disagreement with someone. (e.g., "Those two teams have beef from their last game.")To beef (verb): To complain, grumble, or argue. (e.g., "Stop beefing about the weather."
But
Cow and Ox are English, their meat, beef is French.
That's how English is.
Those times English people were farmers who took care of animalss, and the French used to rule over them and what English farmers produced.