John Gill Commentary Numbers 30:12

"But if her husband made them null and void in the day that he heard them, then whatsoever proceeded out of her lips concerning her vows, or concerning the bond of her soul, shall not stand: her husband hath made them void; and Jehovah will forgive her." — Numbers 30:12 (ASV)

But if her husband has utterly made them void on the day he
heard them
Declaring they were contrary to his mind and will, he disapproved of them, and forbid the carrying them into execution:

then whatsoever proceeded out of her lips concerning her vows, or
concerning the bond of her soul, shall not stand ;
though her husband be dead, or she be divorced from him:

her husband has made them void, and the Lord shall forgive her :
she will neither incur his displeasure for not fulfilling her vow, nor have any punishment inflicted on her: the Targum of Jonathan is,

``if her husband makes them void, and she knows it not and transgresses, it shall be forgiven her by the Lord.''