God continues to speak through Ezekiel about the terrible things that the people of Jerusalem have done. He speaks to the people of Jerusalem as if they were the city itself, and of the city of Jerusalem as if it were a woman. The word "you" is always feminine singular.
A person whom God considers spiritually unacceptable or defiled is spoken of as if the person were physically unclean. The word "impurity" refers to the time of the month when a woman bleeds from her womb. Women were considered to be unclean at this time.