If you disobey Him, you will be cursed in every way, so that you'll be driven mad and want to die. (53 verses describing this!) You'll be sold as slaves back to Egypt.
God covenants with all Israel standing before Moses, through Moses, and with their future descendants. Disobedience will bring curses, future generations will wonder what awful thing happened, and they'll be uprooted from the land.
How this is about Jesus
Jesus took this curse on Himself at the cross. While forgiven Christians may still face consequences for their sins (often to sanctify us), there is no condemnation or punishment for its own sake.
At Jesus' trial, the Jews historically echo this, as they willingly take responsibility for the blood of Jesus onto their heads and their children's heads.
Living in God's ways generally brings prosperity and blessing, though not always.
This chapter applies only to Israel then, as it speaks of uprooting them from the land. God exiled them according to His promise. This is not a curse He holds over every nation's head for disobeying Him. However, disobedience will naturally bring bondage to others: lenders, tyrants, etc.
Let us love obedience to God (the root) more than freedom (the fruit).
Let us obey from gratitude that we have been freed from guilt before God, not from desperation to stay politically or financially free.