An income is a relatively secure and guaranteed continuous stream of capital over a long time period.
To create an income, a capitalist invests in mature and stable companies with a historical favorable track record of dividend payouts. The investment is held as long as the company is stable, profitable and favorably distributing dividends to the shareholders, which can potentially be for decades to come.
Of course a capitalist wants as much value as possible for the invested capital. The stock price fluctuates as the demand for owning a stock varies. An investment is best made when the price is low and the dividend yield is relatively high.