The word hallelujah in Hebrew, as Professor Lipnick shares in the video above, literally means "Let us Praise the Lord." The Bible talks a lot about praising God throughout, but the book of Psalms has the highest concentration of praises. The world psalm means song or hymn, which is why we have so many modern hymns that are taken from these set of scriptures. They were sung during ancient times. Because they were sung, they were used as ways to praise God through singing.
The word hallelujah has traveled into modern language. You hear people many times using the word when things finally come to pass. For example, here in the south when someone has been waiting on a friend or coworker to text back about where they will be meeting tomorrow, may respond by saying, "Praise Jesus!" or "Hallelujah!"
Often times, the Hallelujah Chorus, which would be interpreted as
"Praise the Lord (Hallelujah!), Praise the Lord (Hallelujah!), For the Lord God omnipotent reigneth!"
gets used at weddings as a way of celebrating that the bride and groom finally got married. Needless to say, our culture doesn't fully understand the depths of this word.
Psalm 150 talks about the many ways that we praise God. Most translates put the line "Praise the Lord!" instead of "Hallelujah!" I have substituted in here in the NLT for the sake of us reflecting on the meaning of the word.
We are called to praise God in the good times, and in the bad. We are called to praise him with our voices and with our tears. We are called to use loud noises and soft ones. We are called to worship him in buildings, homes, and in nature. Praising God should be as simple as breathing. It should be our first reaction no matter what our mood is.