Final answer:
The two axes on the Hertzsprung-Russell diagram are luminosity and temperature. The majority of stars fall on the main sequence, which represents a relationship between temperature and luminosity that is followed by most stars.
Step-by-step explanation:
The two axes on the Hertzsprung-Russell diagram can be luminosity and temperature. The H-R diagram is a plot of stellar luminosity against surface temperature, with most stars falling on the main sequence, which extends diagonally across the diagram from high temperature and high luminosity to low temperature and low luminosity. The position of a star along the main sequence is determined by its mass, with high-mass stars emitting more energy and being hotter than low-mass stars on the main sequence.