The Man of Steel (2013) ending shows Superman killing Zod to save a threatened family, and then settling into a double life as a reporter. Spoilers follow.
The final act runs in a clear sequence. Clark destroys the world engine over Metropolis, and the military uses the Kryptonian scout ship from the Arctic to open a portal that sends Zod's crew back to the Phantom Zone. Zod is left behind, and he attacks a family. Clark is forced to kill him and is shaken by it. Afterward the military accepts that he will act on his own terms, and a drone tracking him is called off. Clark then joins the Daily Planet, with Lois and Perry White as colleagues, and continues his life as Clark Kent.
The kill is the film's defining scene because the portal has already used up the one clean way to remove Zod. The Phantom Zone is closed to him, so Clark has no option left that keeps the family alive. Opinion: the quiet newsroom finish is what gives the moment weight, since it shows a hero who has paid a price and gone back to work instead of celebrating.
The setting adds to the reading. According to Reel Chicago, the Metropolis destruction and battle scenes were shot in the Chicago Loop, and Willis Tower stands in for the Daily Planet. The same skyline that is wrecked in the fight is the building where Clark reports for work in the last scene, which ties the ruin and the fresh start together.
The credit structure explains some of the tone. Christopher Nolan is credited with the story alongside David S. Goyer and produced the film, and Zack Snyder directed, so the origin is told as a grounded, large scale drama. That is why the ending feels so different from Superman (1978), where the tone is lighter. Within the series, Man of Steel (2013) is the sixth film in release order, and it is the one that ends by asking what a hero owes the people he saves.
The last beat matters for what comes next. The ending leaves a world that now knows Superman exists, and the later appearances in Batman v Superman: Dawn of Justice and Justice League pick up from that point.