This interactive figure lets you investigate how the temperature and radius of a star affect the amount of energy it puts out every second, which is the star's luminosity.
Luminosity has metric units of Watts (e.g. a 100 Watt light bulb is converting electrical energy into light and heat at a rate of 100 Watts). However, since stars are very luminous (at least compared to most things on a "human" scale, in astronomy typically use units of solar luminosity, $L_\odot$, where the Sun's luminosity is $1 L_\odot = 3.83\times10^{26}$ Watts!