The four cups of wine during the Passover Seder represent the four expressions of redemption promised by God in Exodus 6:6-7: "I will bring you out," "I will deliver you," "I will redeem you," and "I will take you". 

Here's a more detailed explanation of each cup:

The First Cup (Kiddush/Cup of Sanctification):

This cup is blessed and drunk at the beginning of the Seder, marking the start of the Passover meal and symbolizing the sanctification of the holiday. 

The Second Cup (Cup of Plagues/Deliverance):

This cup is drunk after the reading of the story of the Exodus, commemorating the plagues God sent on Egypt and the Israelites' liberation. 

The Third Cup (Cup of Redemption/Grace after Meals):

This cup is drunk after the main meal, symbolizing the completion of the meal and the redemption from slavery. 

The Fourth Cup (Hallel/Cup of Praise):

This cup is drunk at the end of the Seder, after the singing of Hallel (Psalms of Praise), representing the final stage of redemption and praise to God for His deliverance