Training heart-rate zones from your age (and optionally resting heart rate, via the Karvonen method).
Without it, zones are calculated as straight percentages of your max heart rate (220 − age). If you enter resting heart rate, the calculator switches to the Karvonen method, which factors in your heart rate reserve (max − resting) for a more personalized zone.
Using the common age-based estimate: Max HR = 220 − Age. It's a population average, so your true max can vary from this estimate.
They're labels for increasing percentage bands of your heart rate — Warm up is 50–60%, Fat burn 60–70%, Cardio 70–80%, and Peak 80–90% of max HR (or heart rate reserve with Karvonen).