to raise a girl is costlier than one would expect (like how a small bag can hold more than it seems); (lit.) small bag and young woman; young women are fragile and great care must be taken with them (just as with small bags)
Examples (3 in total)
なるほど、彼女はただの小娘みたいね。
I see, she seems to be just a little girl.
あんな小娘など相手にするはずがない。
There's no way I'd bother with a little girl like that.
そう思っていたら、隣の小娘がこう言った。
Just as I was thinking that, the young girl next to me said this.