Devoted Things (Leviticus 27:28-29).
Up to this point if something was not redeemed it could be either used by or sold by the priests. But ‘devoted' things would seem to indicate things irrevocably devoted to Yahweh. This was seemingly the most serious of vows and the devoted thing became most holy to Yahweh and could neither be sold nor redeemed. Either it was kept permanently within the tabernacle or it was burned. Normally such things would be such as for some special reason were to be seen as sacred, possibly with the hope of making the vow more effective.
“Notwithstanding, no devoted thing, that a man shall devote to Yahweh of all that he has, whether of man or beast, or of the field of his possession, shall be sold or redeemed: every devoted thing is most holy to Yahweh.”
If a man ‘devotes' something to Yahweh in this way, then whatever it is, whether man, beast, or field of permanent possession, it is most holy to Yahweh and unredeemable.
“No one devoted, that shall be devoted from among men, shall be ransomed; he shall surely be put to death.”
In the case of a man such a person devoted to Yahweh must be put to death. They are ‘most holy' to Yahweh. This would apply to those who were seen as deserving of the death penalty such as murderers, adulterers, idolaters, blasphemers and so on. They were devoted to Yahweh. They could not then be redeemed. They must be put to death. Compare Achan in Joshua 7.