訓 そら,あ(く) ・ 音 クウ 🔊
漢越音: không
The 穴 (cave, hole) radical over 工: inside the cave there is nothing at all, giving both "empty" and the empty expanse of sky.
Stroke data: KanjiVG (CC BY-SA 3.0) — kanjivg.tagaini.net
空が青いです。 (そらがあおいです)
The sky is blue.