If you are asking how to say "there is only you in the world" in English, one possible way to say it is "You are the only person in the world." Another way to say it is "You are the only one in the world." Both of these phrases convey the idea that the person being spoken to is the only person in the world, but they are slightly different in emphasis. The first phrase emphasizes the person's uniqueness, while the second emphasizes their singularity.
