Antifaz translates to "mask," specifically a masquerade mask that covers only the eyes or upper face. It's a more specific and evocative word than the general "máscara."
In "Carnaval," Juan Luis Guerra uses antifaz to symbolize the pretenses and deceptions people wear in life, much like costumes at a carnival. He sings, "Donde cada quien lleva antifaz, pretendiendo engañar" (Where everyone wears a mask, pretending to deceive), highlighting the theme of hidden truths and eventual revelation.
This song feels like pulling off a mask at a party and realizing everyone else is doing the same thing. Juan Luis Guerra compares life to a disguised party: “La vida es como un baile de máscaras / donde cada quien lleva antifaz” [“Life is like a masked ball / where everyone wears a mask”]. People pretend, they try to trick others, but deep down they know the moment will come when they “tener que quitarse el disfraz / y encarar la verdad” [“have to take off the costume / and face the truth”]. It is a very theatrical image, but he uses it to talk about something uncomfortable and real.
The coolest twist is when he includes himself in the lie. He admits, “Yo también fui un payaso de carnaval” [“I was also a carnival clown”], someone who thought he could “de mentiras vivir hasta el final” [“live off lies until the end”]. That is pretty blunt. On the outside he is laughing, dressed as a clown, but he confesses that “al reír no hacía más que llorar” [“when I laughed I was only crying”]. The song is like a friendly nudge that says: everyone is wearing a mask, some people never want the party to end because they are scared to be honest, but sooner or later the costume comes off.