What does John 20:10 mean?

Peter and John were told, many times, that Jesus would rise from the dead after being executed (John 2:19–22; Mark 9:31; Luke 18:33; 24:46). Those who read these accounts, after two thousand years, might wonder how they could struggle to understand. In the moment, however, they have not yet put all those details together. They came to investigate an empty grave (John 20:1–6), only to see a unique detail (John 20:7–8). The carefully folded face cloth seems to have sparked John's understanding, making him "believe," in whatever sense, that Jesus is alive.

Clearly, neither Peter nor John have fully absorbed the idea that Jesus is physically resurrected. They will return to their homes, and continue to live in a timid, fearful mood (John 20:19). It seems they say nothing of their thoughts to Mary Magdalene, who will remain behind (John 20:11). Jesus will soon appear to them, making all things clear (John 20:20–22).