The kanji 生 is special — it has many meanings and more readings than most kanji.
You’ll often see 生 in compound words like 学生 (student) or 先生 (teacher). These are its on-yomi readings.
But when 生 appears with hiragana — like 生きる (“to live”) or 生まれる (“to be born”) — it uses kun-yomi.
生 can also mean “raw” or “fresh” — as in 生ビール (draft beer). This range of meanings makes it a perfect example of how kanji shifts depending on context.