Of course score is sometimes used as a verb to mean to win points or goals in a game or competition.
“Lionel Messi has scored again!”
The score can be a noun that means the number of points or goals that each team or player has in a game or match.
“The final score was 3 -2.”
For today’s idiom score means the real facts about a situation. This meaning of score is used with the, and someone knows it. Know the score means know the real facts.
“I hate leaders who know the score in private but who lie to the public to try to look better.”
= leaders who know the facts but don’t share them with their people.
“Sorry Jim, I can’t pay you until the job is finished, you know the score.”
= After the job is over I can pay you, but you understand this (situation).
|“20 minutes late for gym class! 50 push ups, you know the score!”|