Note that verse 6 begins a new paragraph which denotes a change in subject

Verses 1-4 were about the world coming to Jerusalem and God's house for learning and judgment in "The Last Days" - During he Millennial  Kingdom of Christ all must come to Jerusalem

Verses 5 calls for Judah to comeback to living in the light of the Lord - as Israel traveled by night through the wilderness the pillar of fire went before them giving them light to walk and not stumble. It also lead them in the path they should follow. The light was troubling to their enemies (protection) - Judah was to come back to living in the knowledge that the LORD was their guiding light, walking in belief and obedience of His Word. They were ot live as if they believed God was able and would do what He promised. (Read Romans 4:3 For what saith the scripture? Abraham believed God, and it was counted unto him for righteousness. with Romans 4:21 And being fully persuaded that, what he had promised, he was able also to perform.)

Exodus 13:21 And the LORD went before them by day in a pillar of a cloud, to lead them the way; and by night in a pillar of fire, to give them light; to go by day and night:

Nehemiah 9:12 Moreover thou leddest them in the day by a cloudy pillar; and in the night by a pillar of fire, to give them light in the way wherein they should go.

Exodus 14:24 And it came to pass, that in the morning watch the LORD looked unto the host of the Egyptians through the pillar of fire and of the cloud, and troubled the host of the Egyptians,

Numbers 14:14 And they will tell it to the inhabitants of this land: for they have heard that thou LORD art among this people, that thou LORD art seen face to face, and that thy cloud standeth over them, and that thou goest before them, by day time in a pillar of a cloud, and in a pillar of fire by night.

Verses 6-9 tells us that God is going to judge Judah because they had turned to their enemies and were became like them. Along with the great wealth of the land were idols of their enemies. Judah was bowing down in worship to these false idols instead of walking in the Light Of The LORD.  The LORD has pulled back His grace and forgiveness and  Judah and Jerusalem would be forsaken of the LORD and be taken by their enemies and their wealth and all they have will taken by their captors. (Isaiah 39:5-6 ¶ Then said Isaiah to Hezekiah, Hear the word of the LORD of hosts: Behold, the days come, that all that is in thine house, and that which thy fathers have laid up in store until this day, shall be carried to Babylon: nothing shall be left, saith the LORD)

Everything they worshipped more than the LORD will be broken down and taken from them.

Verse 10 begins another paragraph - 10 & 11 Tell of That Day when only the LORD will be exalted and men will seek to hide themselves in the rocks to be shielded from His glory -their self pride will be brought low when they see HIM. Read Revelation 6:12-15

Verse 12 Tells of "the day of the LORD" when will come all men who trust in themselves and lift themselves up. When you search the Bible for "the day of the Lord" the verses will contain words such as wrath, destruction, vengeance, terrors, darkness. (The Tribulation period, especially end and the end of the 1000 year reign of Christ)

Isa 2:12 For the day of the LORD of hosts shall be upon every one that is proud and lofty, and upon every one that is lifted up; and he shall be brought low:
Isa 13:6 ¶ Howl ye; for the day of the LORD is at hand; it shall come as a destruction from the Almighty.
Isa 13:9 Behold, the day of the LORD cometh, cruel both with wrath and fierce anger, to lay the land desolate: and he shall destroy the sinners thereof out of it.
Isa 34:8 For it is the day of the LORD'S vengeance, and the year of recompences for the controversy of Zion.

Zephaniah 1:18 Neither their silver nor their gold shall be able to deliver them in the day of the LORD'S wrath; but the whole land shall be devoured by the fire of his jealousy: for he shall make even a speedy riddance of all them that dwell in the land.

Verses 13-21 "The day of the Lord" will also come upon everything the world considers of value. In "That Day" everything (earthy) that man has desired and cherished above what The LORD will become of no value to them and they will cast them away as they seek the rocks. Where man places his faith, trust and desires will be tried when the "day of the Lord" comes

Verse 22 The LORD is pleading with Judah to turn from mere man (life depends upon his breathing), what value is there in a man. Come back to the Light of The LORD, the One who placed the breath in the nostrils of man and can take it away again as He see fit.