A share is a piece of a company. Not a piece of its building or its logo, but a claim on whatever is left after the company pays its suppliers, its staff, its lenders and its taxes. That leftover is what shareholders own.
The return comes from two places. Part of it is the cash the company hands back, the dividend. The rest is the change in what other people are willing to pay for that same claim, which is the price. Ignoring dividends is why price charts quietly understate what investors actually earned over long periods.
The price moves for two reasons that are easy to confuse. Sometimes the business changed: earnings rose, a product failed, a competitor arrived. Sometimes only the mood changed: the same company, the same numbers, a different willingness to pay. Most daily movement is the second kind.
Owning a share also means accepting a queue. If the company fails, lenders are paid before shareholders, and shareholders are last. That is the reason equity is expected to return more than a bond over long periods: you are being paid to stand at the back.
The practical consequence is that the horizon matters more than almost anything else. Over a day, a share price is mostly noise. Over a decade, it tends to follow what the business actually earned. Choosing a horizon is choosing which of those two you are exposed to.
Educational material. Not investment advice.