Hananiah claims to speak for God. A false prophet prophesied that the captives would return from Babylon with all the temple vessels. Jeremiah told the false prophet that he would die that year for prophesying lies, and he did.
This is the fifth month of the Hebrew calendar. It is during the dry season. It is during the last part of July and the first part of August on Western calendars. This was after Zedekiah had been king for three years.