"You have been a refuge for the poor, a refuge for the needy in distress, a shelter from the storm and a shade from the heat. For the breath of the ruthless is like a storm driving against a wall and like the heat of the desert. You silence the uproar of foreigners; as heat is reduced by the shadow of a cloud, so the song of the ruthless is stilled." NIV translation
The song continues with rejoicing over the fact that man's schemes have failed and Jerusalem is now a haven for God's children. The word that is translated here as "have been" is "hayah" and it actually means more like "have become".
This speaks to the fact that the remnant of God's people suffered tremendous persecution under the world system but, now, they are taken care of by Jesus Christ who reigns from Jerusalem. The "song of the ruthless" speaks of the lie that man could band together to overcome the will of God for His city and people.
"On this mountain the Lord Almighty will prepare a feast of rich food for all peoples, a banquet of aged wine - the best of meats and the finest of wines." NIV translation
This period will be a time when the nations bring their best to Jerusalem in honor of the Lord. This feast is a stark contrast to the time of suffering and shortage that the world has just been through.
The bringing of their best into Jerusalem is a sign of acknowledgement that Jesus is, in fact, the King of Kings.
"On this mountain he will destroy the shroud that enfolds all peoples, the sheet that covers all nations; he will swallow up death forever. The Sovereign Lord will wipe away the tears from all faces; he will remove his people's disgrace from all the earth. The Lord has spoken." NIV translation
The final part of this song begins with praise for the fact that the shame and mourning of God's people has been removed and there is great joy. There will be no more death for His people and no more sorrow as they are a bright and shining example for the rest of the world.