Leviticus 8:20

And he cut the ram into pieces; and Moses burnt the head, and the pieces, and the fat.

The cutting of the ram into pieces and the burning by Moses of its head, its pieces, and its fat was one detail in the rites for consecrating the priests. The ram so divided and burned was a burnt offering presented as part of the prescribed ceremony of that consecration. That consecration was the seven-day setting apart of Aaron and his sons for the priesthood, in which Aaron was purified, clothed in priestly garments, anointed, and set apart for God's service. Those consecration offerings prepared them for ministry in the sanctuary before they began serving others.

The account of this consecration belongs to one of the few historical portions of Leviticus, recording part of the sanctuary ritual. The chapter shows Moses setting apart the Levitical order of priesthood to minister before the ark containing the two tables in the Most Holy Place of the typical sanctuary as long as that sanctuary should continue. In this it carried forward through the entire Old Testament period the ministration begun when Moses brought the law down from God. That ministration brought only condemnation and death because it exposed the guilt of sinful people and their exposure to its just penalty with no promise of pardon in itself. Its priesthood offered no sacrifice that could take away sin but could only point penitent sinners forward to the great Sacrifice to be offered for the sins of men.

Like the other details of these sacrifices, this detail had meaning, and the sacrifices with their priesthood, ceremonies, and types point forward to Jesus Christ, the Lamb of God who takes away sin. They find their fuller meaning in His sacrifice, life, and work, and the Levitical sanctuary service with its priesthood and ceremonies served as a type of Christ's priesthood in the heavenly sanctuary. Beyond identifying the service as a type of Christ's priesthood, no further explanation is given of the verse's specific ritual of cutting and burning.