The language in this verse is reminiscent of the time of the exodus. As once the Lord smote Pharaoh with plagues, so he will strike Egypt with blows in the messianic time (the same verb is used in both cases). Egypt will be treated as a true child of God. The blows will not destroy them but will lead to healing and a closer relationship with God.
22 Ainsi l'Eternel frappera les Egyptiens, Il les frappera, mais il les guérira; Et ils se convertiront à l'Eternel, Qui les exaucera et les guérira.