Here the "world" is a metonym for the people who oppose God. Alternate translation: "but the people who oppose God will be glad" (See: [[rc://en/ta/man/translate/figs-metonymy]])
You can translate this in an active form. Alternate translation: "but your sadness will become joy" or "but afterwards instead of being sad you will be very happy" (See: [[rc://en/ta/man/translate/figs-activepassive]])