Amen is a word used in the Bible to express solemn approval and agreement with a statement.  It is often used at the end of prayers.  It is used a total of 59 times: 28 in the Old Testament and 31 times in the New Testament.  For example,

• 1 Chron. 16:36, “Blessed be the Lord, the God of Israel, from everlasting even to everlasting. Then all the people said, ‘Amen,’ and praised the Lord.”
• Psalm 72:19, “And blessed be His glorious name forever and may the whole earth be filled with His glory. Amen, and Amen.”
• Rom. 1:25, “For they exchanged the truth of God for a lie, and worshiped and served the creature rather than the Creator, who is blessed forever. Amen.”
• 1 Cor. 14:16, “Otherwise if you bless in the spirit only, how will the one who fills the place of the ungifted say the ‘Amen’ at your giving of thanks, since he does not know what you are saying?”
• Jude 25, “to the only God our Savior, through Jesus Christ our Lord, be glory, majesty, dominion, and authority, before all time and now and forever. Amen.”