What does John 20:13 mean?
The two men Mary Magdalene sees here are angels (John 20:12). She is looking into Jesus' empty grave (John 20:11), after Peter and John have left (John 20:10). They did so without, it seems, explaining what they saw inside (John 20:3–9), though it was Mary who came to get them in the first place (John 20:1–2).A typical reaction to seeing an angel is abject terror (Luke 1:11–13; 2:9–10; Acts 10:3–4), at least when they appear in a dramatic form. These angels seem to take on a more normal appearance, as they have sometimes done in Scripture (Genesis 19:1–3). Mary's grief doesn't seem to be interrupted by fear. Most likely, she thinks these men have been in the tomb since Peter and John were there.
Another common aspect of angelic encounters is rhetorical questions: they are either obvious or meant to make a point, rather than literally asking for information (Numbers 22:32; Zechariah 1:12; Luke 24:4–5; Acts 1:10–11; Revelation 17:7). Here, the angels know exactly why Mary is upset. But they also know who is standing right behind her, and the conversation which is about to happen (John 20:14–16).