Mary was female and, thus, would never have been able to be a priest.
This is true; yt all of us are called to be Mary-like: the listen with all humility and openness and availability to God; to "hear the Word and keep it," to carry Christrand bring Him forth for the salvation of the world.
It's part of the universalcall to holiness, becdause the really important and really interesting people in Catholicism are not the priests, nor the popes, but the Saints.
And look: if the Blessed Virgin Mary appeared to the Pope, which of the two would drop to their knees?
I think it is talking about the holiness of Mary, as well as the closeness she had with her son, Jesus Christ.