Refers to a place or situation where one is visible to others; often used when discussing behavior, statements, or appearances in a public setting.
It's better to avoid bringing up that topic in public.
彼は公の場でスピーチをするのが苦手だ。
He is not good at giving speeches in public.
Compound of 公 (おおやけ, 'public') + の (possessive particle) + 場 (ば, 'place').