Dividends are cash that a company pays to anyone who owns their stock every 3 months. For example, Apple recently paid a $0.22 dividend per share, with each share costing $128. It may seem small, but it really adds up over time, especially when you use dividends to buy more stock. When you own stock, you make money from its dividends while you own it and capital gains when you sell it.
More info: What Are Dividends