What does 2 Chronicles 30:20 mean?

For there were many in the assembly who had not sanctified themselves: therefore the Levites were in charge of killing the Passovers for everyone who was not clean, to sanctify them to Yahweh.

For a multitude of the people, even many of Ephraim, Manasseh, Issachar, and Zebulun, had not cleansed themselves, yet they ate the Passover other than the way it is written. For Hezekiah had prayed for them, saying, “May the good Yahweh pardon everyone

who sets his heart to seek God, Yahweh, the God of his fathers, even if they aren’t clean according to the purification of the sanctuary.”

The children of Israel who were present at Jerusalem kept the feast of unleavened bread seven days with great gladness. The Levites and the priests praised Yahweh day by day, singing with loud instruments to Yahweh.

Hezekiah spoke encouragingly to all the Levites who had good understanding in the service of Yahweh. So they ate throughout the feast for the seven days, offering sacrifices of peace offerings, and making confession to Yahweh, the God of their fathers.

The whole assembly took counsel to keep another seven days, and they kept another seven days with gladness.