You should take some aspirin to ease your period pain.
What do you think of curing cancer by using an herbal remedy?
Only Viet knows that Koichi has strange powers that can heal injuries and sicknesses.
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means cure, so the verb vocab version is to cure. Don't get this confused with 治る which means "to be healed." This particular verb is when you do the curing. How do you know that? Because when you try to heal them, you mess up, and then they try to sue (す) you.
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: I need you to heal him, and I need you to heal him right now (なお). NOW NOW NOW!
This also shares the reading for 直す, a very similar word you learned previously, which means "to fix." I'm guessing that the Japanese word なおす was only one word ("to fix" and "to cure" are pretty similar, right?). Then, there were two Chinese words for it (as you can see with the kanji), so the one Japanese word got split into two very similar words.