Several parts combine into one character.

官 is a compound ideograph: 宀 (the "roof / house" radical) over 𠂤 (originally a depiction of stacked stones / piled materials). The composite reads as "things piled up inside an official building" = bureau, government office, official, post. The 宀 radical anchors a family of "house / dwelling" characters: 家 (home), 官 (government office), 安 (peace, what is at home), 宅 (residence). 官 names specifically the institutional house — a place where official business is conducted and ranks are accumulated.

Korean reading "gwan." Saturates Korean administrative vocabulary: 官吏 (gwalli, government official), 官廳 (gwancheong, government office), 官職 (gwanjik, official post / civil-service rank), 檢察官 (geomchalgwan, prosecutor), 警察官 (gyeongchalgwan, police officer), 外交官 (oegyogwan, diplomat). Korean political news, legal vocabulary, and bureaucratic discourse all depend heavily on 관.

Mandarin guān, 1st tone. 官 (guān), 官员 (guānyuán, official), 官方 (guānfāng, "official side" = official / authorized — 官方网站 guānfāng wǎngzhàn "official website"; 官方声明 guānfāng shēngmíng "official statement"), 法官 (fǎguān, judge), 警官 (jǐngguān, police officer). 官方 has become a uniquely useful adjective in modern Chinese internet vocabulary: anything endorsed or stated by the proper authority is 官方.

Japanese on-reading カン (kan) — 官 (kan, government official), 官庁 (kanchō, government agency / ministry), 裁判官 (saibankan, judge — Japanese judiciary uses this term), 警察官 (keisatsukan, police officer — full formal name; abbreviated to 警官 keikan in casual usage), 外交官 (gaikōkan, diplomat). Japan has essentially no kun-reading for 官 — the on-reading カン dominates across all senses. Japanese postwar civil service titles built largely on 官 vocabulary.

Memory aid: roof (宀) over piled materials (𠂤) — the official building where business and ranks accumulate.