The word "Tartarus" is a term from Greek religion that refers to the place where evil spirits and wicked men who have died are punished. AT: "he cast them into hell" (See: [[rc://en/ta/man/translate/translate-names]])
Possible meanings are 1) "in chains in a very dark place" or 2) "in very deep darkness that imprisons them like chains." (See: [[rc://en/ta/man/translate/figs-metaphor]])
Here the word "world" refers to the people who lived in it. AT: "he did not spare the people who lived in the ancient world" (See: [[rc://en/ta/man/translate/figs-metonymy]])
# he preserved Noah ... along with seven others
God did not destroy Noah and seven other people when he destroyed the rest of the people who lived in the ancient world.
# reduced the cities of Sodom and Gomorrah to ashes
"burned the cities of Sodom and Gomorrah with fire until only ashes remained"
# condemned them to destruction
Here the word "them" refers to Sodom and Gomorrah and the people who lived in them.
# as an example of what is to happen to the ungodly
Sodom and Gomorrah serve as an example and a warning of what will happen to others who disobey God.