When you buy a share, you own a tiny fraction of a company: its factories, its brand, its customer contracts, and its future profits.
That's why the questions worth asking are business questions. Does it sell more each year? Does it keep any profit? Can it survive a bad year?
The price on the screen is just what other people are willing to pay for that slice today. Over long periods, prices tend to follow the business. Over short periods, they follow the mood.