Fix your posture.
The prince's mistake was corrected and his pride was wounded.
If you can correct my mistakes, I’ll give you a reward.
This word is made up of a kanji with some hiragana attached, ending in an う sound. That means this word is a verb. The kanji itself means "correct," so what is the verb form of that? It would be to correct.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you:
After you correct something for someone, you yell out ta da (ただ) very excitedly. Go ahead and imagine yourself doing this a few times to help you to remember.