The notion of physical fitness is used in two close meanings – General fitness and Task-oriented fitness.
In a more general meaning, physical fitness is a general state of good somatic health and abilities.
A handicapped person may nevertheless be physically fit. Fitness helps them to compensate disability.
Physical fitness is usually a result of regular physical activity, e.g., physical exercise, and proper nutrition.
Cardio is a type of fitness designed to improve cardiovascular strength.
A person may be said to be physically fit to perform a particular task with a reasonable efficiency, for example, fit for military service.