From the perspective of Jungian depth-psychology, it means that there is something about that person that you admire (if the dream was positive) or want to work out (if the dream was challenging or a nightmare). The key is not to relate to the other person. Instead, ask, "What is the issue here for me? What quality does this person have which has activated unconscious interest?" If it is a positive quality, develop it in yourself. If it is a harmful quality, work on releasing your judgments around it.