Why do we say "Amen" after praying?

Here's the answer:

"Amen" is a special way to end our prayers.

The word "amen" means "so let it be" or "it is true." Saying "amen" is a way to finish our prayers, like ending a letter with the words "sincerely" or "love." It's a word that tells God we've said a prayer that we really meant. It shows that we believe God has heard our prayer and will answer it in His perfect way. "Amen" reminds us that God always has everything under control, even the hard things.

Bible Truth

"Give praise to the LORD, the God of Israel, for ever and ever. Let all of the people say, 'Amen!' Praise the LORD" (Psalm 106:48).

"...The prayer of a godly person is powerful. It makes things happen" (James 5:16).