This is the 13932nd most frequent Korean word.
말해주었다
"Told" or "said (to someone)."
The word '말해주었다' is used here to indicate that the speaker told something (the truth) to the friend as an act of communication or disclosure.
나는 친구에게 진실을 말해주었다.
I told the truth to my friend.
In this sentence, '말해주었다' is employed to show that the teacher conveyed an important piece of information to the students.
선생님은 우리에게 중요한 사실을 말해주었다.
The teacher told us an important fact.
'말해주었다' here is used to indicate that the subject conveyed a piece of information or expectation to the listener.