# Josiah kept a Passover to Yahweh
Josiah organized a large Passover celebration and people shared their animals with those without animals to sacrifice. The celebration of Passover was a sign of proper worship by the people.
# in Jerusalem
Yahweh had commanded Moses that all the people of Israel were to go to Jerusalem to celebrate the Passover.
# the fourteenth day of the first month
This is the first month of the Hebrew calendar. The fourteenth day is near the beginning of April on Western calendars.