工 pictures an ancient tool — most scholars see a carpenter's square, others an axe haft or tamping tool. Three strokes that have meant 'skilled work' for over 3,000 years, since the oracle bones.
工 built modern China's vocabulary: 工作 (work — your first must-know compound), 工人 (worker), 工厂 (factory). A person 人 beside 工 makes 'worker'; add 力 (strength) below and you get 功 (achievement). The character even shapes other characters: 左 (left) hides a 工 — the working hand. Simple, industrial, everywhere.
A carpenter's square: top bar, bottom bar, one upright — WORK.
工 is one of the oldest characters still written exactly as it appeared on Shang-dynasty oracle bones.