# and if he did not spare the ancient world

"and if God did not refrain from punishing the people who lived in the ancient world"

# but preserved Noah ... along with seven others

"but protected Noah ... along with seven others."

# Noah, a herald of righteousness

"Noah, a preacher of righteousness." Possible meanings are 1) Noah taught people that they should live righteous lives, or 2) Noah warned people that the righteous God would judge them.

# when he brought a flood on the world of the ungodly

God punished ungodly people by sending a flood that killed them.