Rashi on Numbers 30:7/רש"י על במדבר ל׳:ז׳

1ואם היו תהיה לאיש AND IF SHE BECOMES A MAN’S — (a phrase used for marriage). This refers to a woman who becomes betrothed (ארוסה). Or perhaps this is not so, but it refers to a married woman (one who has joined her husband; cf. Rashi on Leviticus 21:9). When, however, it says, (v. 11) “And if she vowed in her husband’s house”, it is evident that a married woman is being spoken of there, and here, therefore, the text is speaking of one who has been only betrothed. And it (the separate mention of her) is intended to make a different rule about her — that her father and her husband must annul her vow: if the father annulled and the husband did not annul, or the husband annulled and the father did not annul, then this vow is not regarded as annulled, and it is not necessary to state (and it is a matter of course) that if one of them confirmed the vow the other has no power to annul it (Sifrei Bamidbar 153:7; Nedarim 67a).

2ונדריה עליה [AND IF SHE BECOMES A MAN’S] AND HER VOWS ARE UPON HER — It means that she had made the vows being in her father’s house, and her father did not hear them, and so they were neither annulled nor confirmed at the time of her betrothal (cf. Sifrei Bamidbar 153:7).