I’m not sure if I should buy unsweetened coffee.
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means astray and the verb vocab version is to go astray (because you don't just "to astray" now do you?). You can use it if you ever decide to get lost. I'm not sure why you'd do that on purpose, but I don't judge.
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:
If you are going to go astray, one way to do it would be to eat wayyyy too much mayo (まよ). I can't think of a worse way to go astray, personally.