"You are alone."
Translation:Tu es seul.
It could also be singular....
Short version = "tu" and "vous" can mean "you" (singular) in English. Read more here...
"vous" can be singular as a formal address to a stranger or to someone you owe respect to.
in that case that single person can be a man or a woman.
So, all in all, there are 6 possible translations for this English sentence that I invite you to read above.