Flat
noun, な adjective
The kanji and the word are exactly the same with a little hiragana sticking out. Because the hiragana doesn't really indicate what it is, it's okay to assume that they share meanings as well.
Since this word is made up of a kanji plus some hiragana attached, it should use the kun'yomi reading. When learning the kanji, you didn't learn that reading, so here's a mnemonic to help you with this word:
Something is very, very flat. Perhaps someone who doesn't eat much, like a model? Which model? Let's imagine it's Tyra (たいら) Banks.
あの山、平らですね。
That mountain is flat.
これは土を平らにするマシンです。
This is a machine that flattens the ground.
平らなところでもビー玉のレースはできますか？
Can I race marbles even on a flat surface?