The retail industry, excluding wholesale, contributed $482 billion (22% of GDP) and employed 249.94 million people (57% of the workforce) in 2016. The industry is the second largest employer in India, after agriculture. The Indian retail market is estimated to be US$600 billion and one of the top-five retail markets in the world by economic value. India has one of the fastest-growing retail markets in the world, and is projected to reach $1.3 trillion by 2020.
For a person working for a wage, their source of income is their job, or their labor (aka their time that they sell to someone). But you can own a house, and rent it out, and when your renters pay you renter every month, the source of that income check is your rental property, or your house. It would just be called rental income. If you have money in the bank in an account that pays interest, those interest payments are another source of income. We can say the source is interest payments, or we can identify the asset that is generating rent, and say your money in the bank that is generating “rent” (aka interest) is your source of income.