This is a cerebral abscess. There is a liquefactive center with yellow pus surrounded by a thin wall. Abscesses usually result from hematogenous spread of bacterial infection, but may also occur from direct penetrating trauma or extension from adjacent infection in sinuses.
Note the marked dilation of the cerebral ventricles. This is hydrocephalus. Hydrocephalus can be due to lack of absorption of CSF or due to an obstruction to flow of CSF.