@Loid Danga Yes, that's what it means. If you spend time on the zoning map, in the descriptions, and looking at what you can do w listings, it all starts to make sense. DCRA will provide you a free consult to let you know what is allowed on a specific property when you are doing your research.
There are 2 ways I know to rent space in the home you live in, 1) roommates (boarders) and 2) ADU. Boarding is easier. This is when leases do not restrict access to a specific part of the home. Don't believe you even need a BBL (basic business license) when you live in the home.
Building on the excellent info from @Eric Teran, an ADU (Accessory Dwelling Unit, not Affordable DU) is more work. Once you build it out in an R zone, you register w Tax & Revenue, apply for single family BBL online, and register w DHCD. Leases limit access to the ADU so tenants don't get access to the main home. If the ADU is within the main home, no COO is required. If it's a separate structure, a COO is required. If in an RA or RF zone, COO is always required.
If you don't have an ADU and rent the whole home out w/o living in it, you need the registrations above including a COO (cert of occupancy).
If you have 2 homes on the same lot and rent both out w/o living there, you need the registrations above expect the BBL is a 2 family BBL and you need 2 COOs, one for each dwelling. @Jeremy D. I think this is what you have in mind.
If there are 3 or more homes and you rent them all out, that is an apartment building.
The permit/registration requirements for landlords are summarized at https://dcra.dc.gov/page/renta...
The COO process includes notifications from DCRA to neighbors, who have a chance to object - like when you add on a deck, as well as property inspection(s).
The city is encouraging ADUs to increase housing supply. UPO put out the ADU Homeowner's Manual w info on planning, getting free DCRA consultations, licenses, COOs, what inspectors look for, costs, sample ADU lease, etc. My favorite part is about creating an ADU out of a shipping container. But that brings up a whole other topic about lot coverage - for another thread. Link: https://www.upo.org/wp-content...