It's about have an actual aim beyond 'working out' and structuring the workout to reflect this. An example would be a better bench press - working on that and accessory movements to make the bench numbers go up.
So a 'workout' might be just doing chest/pec work like Bench Press and flyes. But being 'intentional' in increasing your bench can and often does include upper back work, rear delt, tricep work and not just that but specific back, delt etc work to increase my pressing power. An example of which (oft used by benchers) would be the JM Press with dumbbells for the tricep.