Mou means already, and shindeiru means dead. Sometimes it might be better to use a person’s last name or first name in place of the pronoun if you are unsure. Omae is the Japanese word for the male “you.” This is an aggressive way to refer to a person. This is a bit like the phrase “hasta la vista,” popularized by the 1991 American movie Terminator 2: Judgment Day.
According to 7ESL, This is Japan, and Medium, the term omae wa mou shindeiru means “you are already dead” in its common English translation.
