What Does Shares Mean?
A unit of ownership interest in a corporation or financial asset. While owning shares in a business does not mean that the shareholder has direct control over the business's day-to-day operations, being a shareholder does entitle the possessor to an equal distribution in any profits, if any are declared in the form of dividends. The two main types of shares are common shares and preferred shares.
Investopedia explains Shares
In the past, shareholders received a physical paper stock certificate that indicated that they owned "x" shares in a company. Today, brokerages have electronic records that show ownership details. Owning a "paperless" share makes conducting trades a simpler and more streamlined process, which is a far cry from the days were stock certificates needed to be taken to a brokerage before a trade could be conducted.
While shares are often used to refer to the stock of a corporation, shares can also represent ownership of other classes of financial assets, such as mutual funds.