SATB

That stands for soprano, alto, tenor, bass. That's just a scoring for choral works common enough to get an abbreviation. You may have noticed if there are choirs in your church that there are the high and lowish female sections and highish and low male sections of the choir.  SATB

Well, that's easy enough. But I also wondered, what's a baritone? Doesn't treble mean something? The three tenors don't sound that high. I never heard them singing falsetto. (That's the higher register of your voice associated with yodeling which, by the way, is really hard whether you enjoy it or not.  Try it.) If you've wondered these things, too, then read on.