Scripture often pictures idolatrous Jews as adulterous people and sometimes as prostitutes. This is not the reference here. The translator should allow this illustration to be vague. (See: [[rc://en/ta/man/translate/writing-apocalypticwriting]])
This possibly refers to the city of Rome, which was known as the city on seven hills. However, the translator should not attempt to identify Rome in the translation.
John uses many different metaphors in this chapter. He explains some of their meanings, but allows them to remain relatively unclear. The translator should attempt to do the same. (See: [[rc://en/ta/man/translate/figs-metaphor]])
This and similar phrases in this chapter contrast the beast with Jesus. Jesus is called "the one who is, and who was, and who is to come" elsewhere in the Book of Revelation. (See: [[rc://en/ta/man/translate/figs-explicit]])
A paradox is a true statement that appears to describe something impossible. This sentence in 17:11 is a paradox: "the beast ... is itself also an eighth king; but it is one of those seven kings." The translator should not attempt to resolve this paradox. It should remain a mystery. ([Revelation 17:11](../../rev/17/11.md))