Aguanile (literally nile water, i.e. "water from the Nile", "holy water") is used in Santeria rituals. Santeria is derived from religious practices of African slaves in the Caribbean.
Willy Colon's arrangement of the song begins with African animal and human sounds – recalling the African origins and traditions prevalent in Latin America.
my favorite part of the song is near the beginning when the singer namechecks the Catholic latin mass by calling Kyrie eleison, Christus eleison.