This polite phrase is used to invite someone to enter a room, house, or building. "どうぞ" adds emphasis and politeness, meaning "please," and "お入り ください" is a polite command meaning "come in" or "enter."

誰かに部屋や家に入るように丁寧に促す時に使います。「どうぞ」は丁寧な言葉で、「お入りください」は「入ってください」の丁寧語です。