Foolish
Stupid
noun, な adjective
The kanji and the word are exactly the same. That means they share meanings as well.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You haven't learned this reading yet, so here's a mnemonic to help you:
A foolish person will take the old road (おろ), instead of the new, safe one. You have to be really stupid to take an old road that's all cracked and full of scary people. Take the new one!
あいつも愚かなことをしたもんだよ。
He does such stupid things.