When I finish school, I'll go shopping.
My life was over when I lost it all gambling.
Hey, man! Back off! I told you to stay away from me until the atomic bomb has finished being dismantled.
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 end and so the verb version of this is to end (or to finish).
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:
It is time to end this. You are the debt collector and so you go to the ower (おわ) to collect what is due. Hey, it's time to end this fool! You are the ower!