It is the name of the gracious, blessing-bestowing Triune God. There are three parts in the Blessing, and the Lord’s name is mentioned three times.
In place of the Lord’s Blessing, the Apostolic Blessings, which is similar in content, can at times be used: “The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Ghost, be with you all”, 2 Cor. 13:14.