Technically speaking, shares represent units of a stock/stocks.
When you own shares or stocks, you own part of a public company, and therefore you have certain rights.
Both words, ‘stock’ and ‘share’, refer to financial securities.
As a shareholder, you own a part of a company. That piece of ownership not only gives you financial rights such as a part of the profit, but you also have the right to vote for certain corporate decisions.