In a basement there is a plastic or metal strip around a section of or all round the exterior walls (foundation). What is it you wonder, looking further you notice that the floor was removed and filled back in and there is a cover with a pipe.
This basement has had a history of wet floors and the solution the homeowner went for was to have the floor adjacent to the foundation trenched, a drain pipe installed with plastic to metal panels against the walls to catch the water on the inside of the walls and channel it into the drain. The drain is connected to a pit with a sump pump in it that operates when the water fills the sump keeping the basement floor dry.
So to answer you question, it’s a “water management system” (not to be confused with damp proofing)