Even though he scolds me, my father thinks admonishing is the solution.
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 admonish, so the verb version is to admonish or to warn.
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:
Your mom started to admonish you so you instantly sat (さと) down. Maybe if she sees you sat down right in front of her, looking guilty and feeling remorseful, she won't yell as hard.