The word "bowl" refers to what is in it. See how you translated this in [Revelation 16:2](./02.md). Alternate translation: "poured out the wine from his bowl" or "poured out God's wrath from his bowl" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Here "darkness" is spoken of as if it were something like a blanket. Alternate translation: "it became dark in all his kingdom" or "all of his kingdom became dark" (See: [[rc://en/ta/man/translate/figs-metaphor]])