The house gets cold, so the thermostat turns the furnace on, then the house warms up, and the thermostat turns the furnace off. In a similar way, stars can regulate the number of fusion reactions happening within the core. To understand how this is done, we use the concepts of hydrostatic equilibrium, the relationship between pressure and temperature, and our understanding that fusion requires high temperatures. This is quite an important concept this concept of balance between several competing processes. The remainder of the energy comes off as radiation that we see.
Conduction is a familiar process.
An example of conduction is when you place a pan on an electric stove. The stove element causes the pan to heat up. On the microscopic level, the atoms in the burner move faster, and they run into the atoms in the pan, causing them to move faster. Conduction will not be important in main-sequence stars , simply because the atoms are not close enough together. Radiation is the process of transferring energy using photons.