This article describes 1) What is a benediction?, and 2) The Aaronic Blessing in Numbers 6:24-26.  

Bible verse quotations below are taken from the English Standard Version (ESV) unless noted otherwise (Ref. 1).

     Consider.  In your own words, how would you define or explain what is a benediction?

     A "benediction" is a declaration of God's blessing, often used to close a worship service.  The word "benediction" means to speak well of (Ref. 2). 

• A benediction is a declaration -- a blessing -- from God to us, not a prayer request from us to God (Ref. 3). 
• A benediction is authorized by God and usually is spoken by a pastor or priest at the end of a worship service or congregational gathering.  In Scripture, we also see examples of written benedictions at the conclusion of Paul's epistles (1 Thessalonians 5:28).  
• A benediction imparts the reality of God's protection, presence, grace, and peace to believers as we go to serve God in the world (Genesis 28:15, Matthew 28:19-20, 2 Corinthians 13:14, Revelation 22:21 AMP, Ref. 4).  
  
  

"The Lord bless you and keep you; the Lord make his face to shine upon you and be gracious to you; the Lord lift up his countenance upon you and give you peace." (Numbers 6:24-26) 
 
     The Aaronic Blessing is the most famous benediction in the Bible (Ref. 5).  It is called "The Aaronic Blessing" because the Lord commanded Moses to instruct Aaron and his sons (the priests) to pronounce this blessing over the Israelites (Numbers 6:22-23).  The Aaronic Blessing confers God's protection, favor, grace, and peace on God's people.

     (1). The Lord is the source of all well-being and good gifts you need for life (Psalm 23:1 NIV, Ephesians 1:3, James 1:17).  In Numbers 6:24-26, the Hebrew word for "the Lord" are the consonants, "YHWH," which the ancient Israelites pronounced "Yahweh" (Ref. 6).   

     (2). The phrase, "The Lord bless you," is saying "the Lord bestow divine favor on you" (Ref. 7).  God's favor is grace, acceptance, and delight (Ref. 8). 

     (3). The phrase, "The Lord ... keep you," is saying, "the Lord guard and protect you" (Ref. 9).  The Hebrew word for "keep" [shamar] means to hedge about, that is, guard and protect (Ref. 9, Psalm 121:7-8).

     (4). The Aaronic Blessing uses a singular "you," not a plural "you," in all three verses (Numbers 6:24-26) (Ref. 10).  The singular you signifies that God blesses us as individuals and that no one is overlooked.  Believers in Christ are included as current recipients and beneficiaries of the Aaronic blessing because of what Christ has accomplished through his shed blood (Ephesians 2:12-14 NIV).

     The phrase, "The Lord make his face shine on you," is saying, "the Lord direct the warmth of his personal presence and favor to you" (Topical Lexicon - Ref. 11).  In Exodus 33:11 and 14 we see the same Hebrew word [panim] used for the Lord's "face" and the Lord's "presence" (Ref. 12). 

The phrase, "The Lord ... be gracious to you," is saying, "The Lord ... bestow unmerited favor and kindness to you" (Ref. 13, Isaiah 30:18 NIV).

     "Countenance" here in verse 26 and "face" in verse 25 are the same Hebrew word, panim (Ref. 12).

The phrase, "The Lord lift up his countenance upon you" says in a strong form that "the Lord will look directly to you in his full attention" (Ref. 14). 

The result of the Lord looking directly at us is that he gives us his peace.  The Hebrew word in Numbers 6:26 for peace is the famous word, shalom [pronounced shah-LOHM] (Ref. 15).  Shalom includes peace, completeness, welfare, well-being, safety, and prosperity (Lexical Summary - Ref. 15).  Shalom is rooted in a harmonious, covenant relationship with God, secured by the LORD’s promises, and sustained by obedience (Topical Lexicon - Ref. 15).  Shalom -- the peace and wholeness which comes from God -- forms the climax and conclusion of this wonderful benediction (Ref. 14). 

     Summary.  The Aaronic Blessing in Numbers 6:24-26 is a three-fold priestly benediction where God promises to actively protect and bless [bestow divine favor on] his people.  It invokes God’s presence [literally, God's "face"] to "shine" upon us and direct God's undeserved grace to us.  Finally, it culminates in a blessing of shalom, granting a deep, divine peace that encompasses wholeness, security, and inner well-being.

Related lessons 
"The Meaning of God's Favor" - Psalm 30:5

References
1.  https://www.biblegateway.com/versions/English-Standard-Version-ESV-Bible/ 
2.  https://www.etymonline.com/search?q=benediction
3.  https://www.christurc.org/blog/2012/03/15/the-benediction-its-content-source-and-object
4.  https://biblehub.com/greek/2127.htm
5.  https://www.crossway.org/articles/10-things-you-should-know-about-the-most-famous-blessing-in-the-bible/
6.  https://www.faithwriters.com/article-details.php?id=216366
7.  https://www.dictionary.com/browse/bless
8.  https://www.scriptureway.com/home/the-meaning-of-gods-favor
9.  https://biblehub.com/hebrew/8104.htm
10.  https://biblehub.com/interlinear/numbers/6-24.htm
11.  https://biblehub.com/hebrew/215.htm
12.  https://biblehub.com/hebrew/6440.htm
13.  https://biblehub.com/hebrew/2603.htm
14.  https://biblehub.com/commentaries/pulpit/numbers/6.htm
Pulpit Commentary - Numbers 6:26
15.  https://biblehub.com/hebrew/7965.htm