What does Isaiah 19:22 mean?

The era described in this part of chapter 19 seems to be in the future—certainly the extremely far future, from Isaiah's point of view. This scene appears to be set in the time when the Messiah reigns over world (Isaiah 2:1–5; Revelation 20:1–4). Isaiah is pointing to this time when Egypt will no longer be the object of God's judgment as a foreign nation. Instead, the Egyptian people will repent and turn fully to the God of Israel as their own God. They will worship Him as Israel does, with sacrifices, offerings, and the fulfillment of vows (Isaiah 19:19–21).

Now the prophet adds that the Lord's relationship with Egypt will be like His interactions with Israel in another way. He will strike Egypt as a parent disciplines a child and not as the Lord strikes down the enemies of Israel in judgment. He will strike Egypt and they will turn back to Him and ask for mercy. Then the Lord will heal and restore them. This idea would have been shocking to Israel in Isaiah's time. Egypt would eventually become a people in service to the God of Israel instead of a people suffering under His judgment.