She is that "woman" who is present in the central salvific event

"When the time had fully come, God sent forth his son, born of woman." With these words of his Letter to the Galatians (4:4), the Apostle Paul links together the principal moments which essentially determine the fulfillment of the mystery "pre-determined in God" (cf. Eph 1:9). The Son, the Word one in substance with the Father, becomes man, born of a woman, at "the fullness of time". This event leads to the turning point of man's history on earth, understood as salvation history. It is significant that Saint Paul does not call the Mother of Christ by her own name "Mary", but calls her "woman": this coincides with the words of the Proto-evangelium in the Book of Genesis (cf. 3:15). She is that "woman" who is present in the central salvific event which marks the "fullness of time": this event is realized in her and through her.

Thus there begins the central event, the key event in the history of salvation: the Lord's Paschal Mystery.

Pope John Paul II. Apostolic Letter Mulieris dignitatem, n. 3-4, August 15, 1988