The blood of the Passover Lamb provided protection from the destroyer. The blood of the Passover Lamb led to their deliverance and freedom from slavery.
The shedding of blood provided a covering for sin through an acceptable sacrifice. The shedding of blood made a covenant with God possible when He established a covenant with Abram with blood. It made possible complete protection from the destroyer. The blood consecrates or sanctifies unto the Lord. The shedding of blood made complete atonement and removing of sin possible.
This is a Psalm of protection, immunity, deliverance and longevity. In this life, we need to practice a 3-fold posture of life - Relationship, declaration and boldness.