Several parts combine into one character.

廣 (traditional) is a phono-semantic character: 广 (a large building open on one side) for meaning and 黃 (yellow) for sound. From a great structure open on all sides without walls came "wide, broad." The shinjitai reduced the inner 黃 to 厶 giving 広; the simplified dropped 黃 entirely, leaving just 广.

So the form splits three ways: traditional (ko/en/es) is 廣, Japanese shinjitai (ja) is 広, Chinese simplified (zh) is 广 — sharply different by mode (廣 15 strokes vs 広 5 vs 广 3).

Korean hanja-sound "gwang": 廣告 (gwanggo, advertisement), 廣場 (gwangjang, plaza), 廣大 (gwangdae, vast), 廣域 (gwangyeok, wide area), 廣範圍 (gwangbeomwi, wide scope). Korea uses the traditional 廣.

Mandarin: guǎng, 3rd tone. 广告 (guǎnggào, advertisement), 广场 (guǎngchǎng, square / plaza), 广东 (Guǎngdōng, Guangdong province), 广播 (guǎngbō, broadcast), 推广 (tuīguǎng, to promote widely). Common in place names 广东 (Guangdong), 广州 (Guangzhou).

Japanese: on-reading コウ (kō), kun ひろ.い (hiroi). 広い (hiroi, wide), 広告 (kōkoku, advertisement), 広場 (hiroba, plaza), 広島 (Hiroshima), 背広 (sebiro, a business suit). It is the character in the place name 広島 (Hiroshima).

Memory aid: a large building open on one side (广) — broad space without walls is "wide."