I could see the oil leak starts from this black rounded part (1st picture). The vehicle is Honda CR-V 2001. Thanks.
It's called a "Camshaft Cap Gasket" or "Cylinder Head Plug". It seals the end of where your camshaft goes to keep the oil in the right places (ie: Inside the engine.) The OEM part number for this is: 12513P72003
Its a Cylinder Head Plug or Camshaft Cap Gasket. Either name will work.