en_tn/rev/11/12.md

Then they will hear

Possible meanings are 1) the two witnesses will hear or 2) the people will hear what is said to the two witnesses.

a loud voice from heaven

The word "voice" refers to the one who speaks. Alternate translation: "someone speak loudly to them from heaven and" (See: rc://en/ta/man/translate/figs-metonymy)

say to them

"say to the two witnesses"