"Let the priests, who minister before the Lord, weep between the temple porch and the altar. Let them say, 'Spare your people, O Lord. Do not make your inheritance an object of scorn, a byword among the nations. Why should they say among the peoples, "Where is their God?"'" NIV translation
The prophet informs the people that this change of heart must begin with the priests. They must openly repent and cry out to the Lord for forgiveness for themselves as well as the rest of the people.
"Then the Lord will be jealous for his land and take pity on his people." NIV translation
The land that God gave His people is special to Him even though we do not know why He chose that place. He cares for that land as well as for His people and, when they turn to Him in repentance, He will hear and act on their behalf.
This repentance is the same way that we come to faith in Jesus Christ and become His children.
"The Lord will reply to them: 'I am sending you grain, new wine and oil, enough to satisfy you fully; never again will I make you an object of scorn to the nations.'" NIV translation
When God's people humble themselves and turn back to Him, He will provide for their needs. He will also raise them up to be honored instead of scorned. This verse speaks of the coming millennial reign as we see in Revelation 20.
"'I will drive the northern army far from you, pushing it into a parched and barren land, with its front columns going into the eastern sea and those in the rear into the western sea. And its stench will go up; its smell will rise.' Surely he has done great things." NIV translation
These words were partially fulfilled with the Assyrians but its complete fulfillment comes on the Day of the Lord. On that day, God will judge the armies that are led by Russia (the northern army see Ezekiel 38 & Revelation 19).