What does Matthew 27:58 mean?

Joseph, a wealthy member of the Jewish ruling council, the Sanhedrin, has come forward to help the friends of Jesus deal with His body (Matthew 27:50). Joseph is a secret follower of Jesus (John 19:38) who now decides to act boldly. He goes to Pilate and asks if he can take Jesus' body away now that He has died.

We know from Mark's gospel that Pilate is surprised Jesus is already dead (Mark 15:44). Crucifixions could sometimes last for days; the cruel process was designed with that in mind. The fact that Jesus was viciously flogged and beaten prior to the crucifixion (John 19:1–4) likely made His death much quicker. While Romans often left criminals to rot as a warning, this was an offensive practice to Jews (Deuteronomy 21:22–23). With a major religious feast at hand (John 19:31; Matthew 27:62), Pilate would have no reason not to let the dead be buried immediately.

Pilate confirms with a centurion that Jesus is dead (John 19:31–34) and agrees to give the corpse to Joseph. The gospel writers are careful to clarify, repeatedly, that Jesus was entirely and unmistakably devoid of life. This was meant to combat false rumors that He may have not truly died and was not therefore truly resurrected.