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inexperienced (in life experience); unsophisticated; green; wet behind the ears
inexperienced (in love); innocent; naive; simple
「生」 has other readings with different meanings.
あの子はまだうぶだよ。
That kid is still naive.
彼女は素直で生な性格をしている。
She has a straightforward and naive personality.
うぶな性格のせいで騙されやすい。
Because of her naive character, she's easily deceived.