What do astronomers mean when they say that the sun makes energy by hydrogen burning?

It seems that you have missed the necessary options for us to answer this question so I had to look for it. Anyway, here is the answer. What astronomers mean when  they say that the sun makes energy by hydrogen burning is that, the Sun is fusing hydrogen into helium and releasing energy. Hope this helps.

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stands for electromotive force and it is measured in volts. despite its name, it is not actually the force in the sense of being a "pushing" or "pulling" (not measured in newtons).an equation that relates emf,  ℰ,  to a battery's terminal voltage, v, current, i, and internal resistance, r, is    ℰ = v + irin this case, the emf can be interpreted as a voltage—a difference in electric potential.i would not say that it would be considered an energy. if emf can be defined as the energy/work per a unit charge from a battery or other electric source, then it is not strictly energy.