The word "bowl" refers to what is in it. See how you translated this in Revelation 16:2. AT: "poured out the wine from his bowl" or "poured out God's wrath from his bowl" (See: rc://en/ta/man/translate/figs-metonymy)
This is where the beast reigns from. It may refer to the capital city of his kingdom. (See: rc://en/ta/man/translate/figs-metonymy)
"Darkness" here is a metaphor, in which ungodliness is like a blanket, obstructing everything from God's influence. AT: "ungodliness was over all its kingdom" (See: rc://en/ta/man/translate/figs-metaphor)
This refers to the people in the beast's kingdom.