With $200,000 a year in passive income, I would have enough income to provide for a family of up to four in San Francisco, given we bought a modest home in 2014. Now that we have a son, I'm happy to say that $200,000 indeed does seem like enough, especially if we can win the public-school lottery to avoid paying $20,000 to $50,000 a year in private-school tuition.
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.