What does Hebrews 9:16 mean?

In this passage, the writer of Hebrews is explaining why the sacrifice of Jesus Christ is superior to that of the old covenant. Animal sacrifice can only do so much to cover human sin. In truth, those sacrifices can only provide ritual purity—they cannot remove the penalty of sin. Jesus, as a man (Hebrews 2:17–18), and one who is sinless (Hebrews 4:15), can offer a single, once-for-all sacrifice which actually covers the penalty for all human sin. This truth is not something which rejects the old covenant. Instead, this is a fulfillment of it. God's intent for the old covenant was as a sign and symbol of things to come (Hebrews 9:23–24).

This verse uses the same Greek word used for terms such as covenant and testament. However, in context, it refers to a slightly different idea. The ESV translates this term as a "will," which is less prone to confusion. The point being made here is that certain legal agreements only take effect upon the death of the one who wrote the will. Verses 16 and 17 both reference this point, leading to the writer's broader goal. The purpose of this statement is to show that sacrifice—represented by blood—has always been necessary to confirm a covenant with God, and to forgive sins. Once again, this demonstrates that the components of the old covenant were meant as symbols of the new covenant.