I may not have explained myself very well. A resting heart rate is a general tool used in fitness to test a person's general level of health. Many things effect your resting heart rate, diet, excercise, stress, smoking, high cholesterol, diseases, age, elevation, etc etc. BUT by guaging your heart rate, you can view your progression. An average person's heart rate is typically between 60-70 depending on age group. An "athlete" or anyone that works out heavily, will have a much lower restiung heart rate. Long distance runners stay around low 40's.
This is NOT the ONLY way to gauge progress. Testing VO2 levels is also a way. Doing intense exercise until reaching your target heart rate then guaging how quickly it drops is another good test.