So what does this tell us about stars?
By characterizing stars in terms of physical quantities, e.g. temperatures and chemical abundance, we can begin to understand how they work and how they could affect their immediate environment (very important for any life in the vicinity).
Later in the semester we'll discuss habitable zones around stars. The habitable zone is essentially where conditions are right for liquid water to exist on a terrestrial planet.
This depends on the kind of star --- that's why being able to
characterize stars is important.