The Cuban Cardio Mass Gain Workout Plan aims to help users get stronger, bigger, and increase muscle mass through a 7 day split routine focusing on upper body, lower body, and full body exercises. Key aspects include training to muscular failure without counting reps, incorporating both high volume and intensity workouts, and consuming extra calories and protein to support muscle growth. The plan provides sample exercises for each day, focusing on compound lifts, and recommends post-workout nutrition including protein and carbohydrates to support muscle building.