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. Alternate translation: "People in the future generations" (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-metaphor]])
Here "generation" represents the people of that generation. Alternate translation: "the people of the next generation" or "their children" (See: [[rc://en/ta/man/translate/figs-metonymy]])