In layman terms equity is nothing but ownership. There are various types of equities however in stock market world it is known as shares or stock. How much you own a equity in a particular stock refers to as equity holding.
In the accounting terminology or corporate world, equity (or more commonly, shareholders’ equity) means the amount of capital contributed by the owners. In other words the difference between a company’s total assets and its total liabilities. If a person owns 1000 shares of total 100000 shares, then he owns 1% of the company.