Several parts combine into one character.

餅 is a phonetic-semantic compound: 食 (food / eating) + 并 (bìng, "to combine / unite" — providing the sound). The composite reads as "food made by combining grains" = a grain-based cake or paste. Here's the fascinating divergence: the same character 餅 names different foods across CJK regions. In Japan and Korea, 餅 means "rice cake" — sticky pounded glutinous rice. In China, 饼 means "flatbread / pancake / round flat baked good" — wheat-based, not rice-based. Same character, two utterly different foods.

Korean reading "byeong." Korean uses the native word tteok for rice cakes; the Sino-Korean 餅 (byeong) is essentially extinct in everyday speech. Compounds: 糕餅 (gobyeong, "cake / cookie" — generic), 餅麵 (byeongmyeon, classical compound). Korean rice-cake culture (tteok-munhwa) is rich — songpyeon (half-moon stuffed rice cakes), garaetteok (cylindrical rice sticks for tteokguk soup), siruttteok (steamed-layered rice cake), injeolmi (chewy rice cake rolled in soybean powder) — but the Sino-Korean character 餅 plays no everyday role.

Mandarin bǐng, 3rd tone (simplified 饼). Mainland Chinese 饼 specifically means flatbread, biscuit, or pancake-style food: 烙饼 (làobǐng, "branded flatbread" = unleavened pan-cooked flatbread), 月饼 (yuèbǐng, "moon-cake" — round dense pastry filled with lotus paste, eaten at Mid-Autumn Festival), 煎饼 (jiānbing, "fried-cake" = jianbing, a thin egg crepe sold from street carts in northern China), 馅饼 (xiànbǐng, stuffed flatbread), 披萨饼 (pīsà bǐng, "pizza-cake" = pizza, since Italian pizza is conceptually a 饼). Chinese 饼 is always wheat-based and flat.

Japanese on-reading ヘイ (hei) is rare. Kun-reading もち (mochi) carries the entire concept: 餅 (mochi, glutinous rice cake — pounded sticky rice formed into chewy blocks), 餅つき (mochitsuki, the New Year tradition of pounding mochi with mallets), 草餅 (kusamochi, mugwort mochi), 大福 (daifuku, "great fortune" = mochi stuffed with sweet azuki paste). Mochi is integral to Japanese New Year culture — お正月 (oshōgatsu) involves eating special mochi 鏡餅 (kagamimochi, "mirror mochi") and 雑煮 (zōni, mochi soup).

Memory aid: same kanji 餅, different food across CJK — Japan/Korea = sticky rice cake (mochi/tteok); Mainland China = flatbread / pancake.