## everlasting joy will be on their heads ##

This uses a person's head to mean the person as a whole. This emphasizes that they will be totally joyful. (See: [[rc://en/ta/man/translate/figs-metonymy]])

## gladness and joy will overtake them;  sorrow and sighing will flee away ##

Isaiah describes these emotions as if they are persons who can run towards or away from God's people. This means these people will only be happy and never sad. (See: [[rc://en/ta/man/translate/figs-personification]])