John Gill Commentary Numbers 30:16

"These are the statutes, which Jehovah commanded Moses, between a man and his wife, between a father and his daughter, being in her youth, in her father`s house." — Numbers 30:16 (ASV)

These are the statutes which the Lord commanded Moses between
a man and his wife
Relating to vows made by the wife, and confirmed or disannulled by the husband: Aben Ezra adds, if she is at age or in puberty, understanding it of a married and not a betrothed wife:

between the father and his daughter ;
if she is not at age, as the same writer observes; for if she is at age he has nothing to do with her vows:

[being yet] in her youth ;
not at age, being not twelve years and one day old:

in her father's house ;
in his power and jurisdiction, and at his disposal, and so could make her vows void or firm, as he pleased:

This power of ratifying or disannulling vows an husband had over his wife, and a father over his daughter, to prevent imprudent and extravagant vows, and the too frequent use of them, the consequences of which might be bad in families.