Here "A generation" represents the people of a generation. The phrase "to come" speaks about a future time as if it were something that travels and arrives somewhere. AT: "People in the future generations" (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-metaphor]])
# the next generation
Here "generation" represents the people of that generation. AT: "the people of the next generation" or "their children" (See: [[rc://en/ta/man/translate/figs-metonymy]])
# of the Lord
"about the Lord" or "about what the Lord has done"
The abstract noun "righteousness" can be stated as an adjective. AT: "tell of the righteous things he has done" (See: [[rc://en/ta/man/translate/figs-abstractnouns]])