Can someone kindly tell me what she meant?

I think it’s meant to be like a snide comment where all the things he doesn’t like in his daughter is considered manly so when she says “I hope she grows into a man” it’s suppose to be like a “haha the wrong part is changing, opposed to her “in feminine” behaviour changing I guess she should just become a man. Idk if that made sense or not. But this also could’ve just been a translation error lol

*un-feminine

It wasn’t an error. It’s bc the father was complaining about his daughter being a “silly girl” and demeaning her bc she’s a girl. So when he says he hopes she’ll grow out of it, Mildred responds by saying she hopes she becomes a man bc she’s criticizing how the father is just complaining that his child is acting out of turn for a girl. It’s like he despises having a daughter. The other comment responding to you also said this, but the traits she displays would be acceptable and admirable if she were a son, so Mildred’s comment is pointing out that the father would be pleased if she wasn’t a girl, basically.