Lesson
Moral, Teachings
noun, verbal noun
At least way back in the day, things that teach instructions to people are things that teach a lesson, moral, or teachings. Back in the day, lots of learning was done through storytelling, and storytelling taught lessons and morals, thus, this word.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
コウイチの話から、どんな教訓がえられましたか？
What moral can you draw from Koichi's story?
この教訓を無だにはしません。
I'll keep this lesson in mind.
前職から学んだ最大の教訓を教えてください。
Tell me about the biggest lesson you learned from your previous company.