圣·
玛丽镇 is a generic Chinese rendering used for various Anglophone or Francophone towns named St. Mary's, St. Marys, or Sainte-Marie (e.g. in Ontario, Pennsylvania, the Caribbean). The middle dot (·) is the standard Chinese separator for Western names;
镇 means 'town/township.' Reading order:
圣 (saint) +
玛丽 (Mary) +
镇 (town).