This is the 318th most frequent Japanese word.
卵
Egg.
Here, 卵 refers to eggs as a food ingredient, commonly used for cooking and eating.
朝ごはんに卵を食べます。
I eat eggs for breakfast.
In this sentence, 卵 is metaphorically used to describe someone as being in the 'budding' stage of developing a skill or profession.
彼はまだ科学者の卵だ。
He is still a budding scientist.
Here, 卵 refers to literal bird eggs found in a nest, indicating its biological and natural context.