Label is a small piece of paper, fabric, plastic etc. attached to an object and giving information about it. Similarly when we put the label of Jesus blood by sprinkling it on us. It inform and speaks better for us to God and cried out to God for Favour (Hebrew 11:24). Blood of Abel was cried out for Judgment but blood of Jesus cried out for Mercy. It speaks to God that you are Righteous and worthy to get His Favour.