>>66525263Japanese has two primary systems for reading kanji: 'on'yomi' (音読み, the Chinese-derived reading) and 'kun'yomi' (訓読み, the native Japanese reading). 食 in 食物 is read using its 'on'yomi' reading "shoku", while in 食べ物, it uses the 'kun'yomi' reading "tabe," derived from the verb "taberu" (to eat).
べ in 食べ物 is hiragana, in this case, it turns the kanji 食 into the verb "taberu."