'Obligations' in the Bible

But if her father prohibits her on the day he hears about it, none of her vows and none of the obligations she put herself under are binding. The Lord will absolve her because her father has prohibited her.

and her husband hears about it and says nothing to her when he finds out, her vows are binding, and the obligations she put herself under are binding.

If her husband says nothing at all to her from day to day, he confirms all her vows and obligations, which are binding. He has confirmed them because he said nothing to her when he heard about them.