Okay kiddo, let me explain what mass means when it comes to music. Mass is a type of religious music that people sing during a Catholic Church service. It's like a big choir of singers who sing together in different parts or voices.
You know when you sing 'Happy Birthday' with your friends and some of you sing the high part while others sing the low part? That's kind of what happens with mass music too. There are different parts called soprano, alto, tenor, and bass. They all come together and sing different melodies to make a beautiful harmonic sound.
The music has been around for hundreds of years, and it was first written in Latin. People who sang mass music would practice a lot to make sure they knew their melody perfectly. When they sang in church, it was like they were speaking to God.
Nowadays, some churches still use mass music during their services, but they might sing it in different languages. It's still a way for people to come together and feel connected to their faith through song.