Your health is the condition of your body. If you barely get any sleep and only eat frozen pizza and jellybeans, you probably have poor health.
Health comes from the old English word for "whole," and you can think of it as the state of your whole being — both body and mind. We use health to talk about bodies and people, but also to talk about whole systems. If you lost your job, you might be worried about the health of your finances. If a bad manager provokes employees to be unproductive, investors might be worried about the health of a business.