pea是豌豆，pod是荚果，like two peas in a pod别理解成“豆荚里的两颗豌豆”，真实含义是一模一样，极其相似，非常相像。

【例句】
The twins are like two peas in a pod. I can't tell who's Betty and who's Jessie.
那对双胞胎长得一模一样。我分不出来谁是贝蒂，谁是杰西。

Betty and Jennifer are as alike as two peas in a pod, so it's no wonder people sometimes mistake them for sisters.
贝蒂和詹妮弗就非常相像，所以难怪人们有时会误以为她们是姐妹。