This is a goodbye song, and a heavy one. Peter Manjarrés and Poncho Zuleta sing to a brother who has died, and the vallenato opens with a question: "Cómo hago yo esta canción" (How do I make this song), when "tengo el corazón llenito de dolor" (my heart is full to the brim with pain). That little "-ito" on llenito is worth noticing: Spanish puts diminutives on feelings to make them more tender, not smaller.
The chorus is the line you will remember: "Hasta luego, hermanito lindo, esta despedida ha sido cruel" (See you later, dear little brother, this farewell has been cruel). Notice it is "hasta luego", not "adiós": he refuses to say a final goodbye. Later verses praise the brother as "correcto y honesto" (upright and honest) and wish him peace with "Que descanses tranquilo" (May you rest peacefully). One handy idiom: "una falta grande tú le vas a hacer" means your family is going to miss you a lot, since "hacer falta" is how Spanish says someone is missed.