Leviticus 27:7
And if it be from sixty years old and above; if it be a male, then thy estimation shall be fifteen shekels, and for the female ten shekels. And if it be from sixty years old and above; if it be a male, then thy estimation shall be fifteen shekels, and for the female ten shekels.
For a person sixty years old and above who is dedicated by a vow, the estimation is fifteen shekels for a male and ten shekels for a female. It belongs to the laws of vows and redemption showing how dedication was carried out in Israel. Such a person was not to be sacrificed, for the stated value could be paid into the Lord's treasury instead of giving the person. When a vow concerned something unlawful to offer, such as a human offering, its value could be assessed and paid instead, which distinguishes fulfilling a vow by valuation from committing a forbidden human sacrifice.
The regulations in Leviticus 27:1-8 provided a way to meet a vow by the prescribed valuation rather than carry out a harmful act, so Jephthah could have sought release from his vow under them. The verse is part of the law of anathema, meaning a curse or ban, properly something set apart, separated and devoted. It denotes absolute, irrevocable and entire separation of a person from the communion of the faithful, from the number of the living, or from the privileges of society, or the devoting of any man, animal, city or thing to be extirpated, destroyed, consumed and annihilated.