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.