Parca refers to the Grim Reaper or personified Death, often depicted as a cloaked figure. It's a more poetic and less common word for 'death' than muerte.
In the song, the lyric "Nadie de la parca se puede escapar" (No one can escape the grim reaper) delivers a powerful and somber message about the inevitability of fate, especially in the context of the violent life described in the lyrics. This word adds a dramatic and memorable touch, making it stand out.
This song tells a dramatic story from start to finish, like a short action movie. The narrator begins by explaining how he got into a dangerous line of work, saying he was just "buscando billete para progresar" (looking for money to get ahead). He becomes successful, but that success attracts dangerous enemies. Things get personal when his rivals try to kidnap his daughters, a line he refuses to let them cross. He makes it clear that no one messes with his family.
He hunts down the men who threatened his children, intending to settle the score. But when he arrives, kicking down the door, he finds he's walked into a trap. The final lines describe a gunfight where he's outmatched by an R-15 rifle. His last thought is about karma, suggesting that even though he lost, the person who killed him will eventually face their own end, because as the song says, "Nadie de la parca se puede escapar" (No one can escape the grim reaper).