Note: There will be some spoilers from Action Comics #957 and Superman: Rebirth #1.
Death in comics happens all the time. Characters die, and writers figure out a way to bring them back. Just recently, we saw the death of Superman from the 2011 New 52 DC Universe reboot and the return of the pre-reboot Superman. Basically, the newer version of Superman died, but there's still the original version that has been living a quiet life in hiding with his wife and son.
With Superman's "death," Lex Luthor decided to declare himself the new Superman for Metropolis. During a public speech, the original Superman decided to confront Lex and revealed himself to the world. This resulted in the appearance of another character.
As Superman and Lex began their confrontation, Jimmy Olsen informed Perry White at the Daily Planet a reporter was needed at the scene. One reporter immediately jumped at the chance to cover it, and Perry seemed a little surprise at the sound of his voice.
Jimmy soon comes face-to-face with the reporter. It's none other than Clark Kent.
This is where things get confusing.
The New 52 Superman's secret identity was discovered, and he was being blackmailed. Lois eventually exposed the secret in order to save Superman's life and free him from being controlled by his enemy. The world knew Superman and Clark Kent were the same person.
This Superman is the one that died fighting another enemy while also dealing with Kryptonite poisoning that was killing him. The pre-New 52 version of Superman figured he could revive his fallen counterpart by putting his remains in a Kryptonian regeneration matrix, as he was revived during his [classic] death at the hands of Doomsday (in 1993). Unfortunately, this world's Fortress of Solitude didn't have a regeneration matrix, so the deceased Man of Steel was buried next Ma and Pa Kent in Smallville.
The question remains: If the only existing Superman is busy talking to and fighting Lex, how can there be a Clark Kent on the scene reporting the events? We'll have to keep reading to find out what's going on. Stay tuned for more information as it comes in.