Hallelujah means to praise
God. It is considered the highest praise by some Chistians, and litterally means "Let us praise
God".
Hallelujah is also sometimes considered halleluyah, because thats how its pronounced, and because
God's names are "Jahova" or short form "Jah", or "Yahwah", or a short form "Yah", which composes the ending of the word.