en_tn/rev/09/15.md

The four angels who had been prepared for ... that year were released

This can be stated with an active form. Alternate translation: "The angel released the four angels who had been prepared for ... that year" (See: rc://en/ta/man/translate/figs-activepassive)

The four angels who had been prepared

This can be stated with an active form. Alternate translation: "The four angels whom God had prepared" (See: rc://en/ta/man/translate/figs-activepassive)

for that hour, that day, that month, and that year

These words are used to show that the time to release the angels is a specific, chosen time and not just any time. Alternate translation: "for that exact time" (See: rc://en/ta/man/translate/figs-parallelism)