en_tn_condensed/rev/08/08.md

The second angel

"The next angel" or "Angel number two" (See: rc://en/ta/man/translate/translate-ordinal)

something like a great mountain burning with fire was thrown

This can be stated in active form. Alternate translation: "the angel threw something like a great mountain burning with fire" (See: rc://en/ta/man/translate/figs-activepassive)

A third of the sea became blood

The fraction "A third" can be explained in translation. Alternate translation: "It was like the sea was divided into three parts, and one of those parts became blood" (See: rc://en/ta/man/translate/translate-fraction)

became blood

Possible meanings are it 1) "became red like blood" or it 2) really became blood. (See: rc://en/ta/man/translate/figs-simile)