You can understand and say one of the most famous phrases by Kenshiro in Fist of the North Star.
You are already dead.
This has been quoted from Fist of the North Star.（アニメ 北斗の拳からの引用）
One by one
お前（おまえ） → you
は → no meaning
もう → already
死んでいる（しんでいる） → dead
Note 1: Fist of the North Star in Japanese
That is 北斗の拳（ほくとのけん） which was on TV during 1980s in Japan after its manga series started to be published. The main character is ケンシロウ who says the key sentence in this lesson.
北斗（ほくと） means ‘the North Star’ and 拳（けん） means ‘fist’.
ケンシロウ has the seven scars on his chest which look like the shape of the North Star (the Big Dipper or the Plough).
Note 2: お前（おまえ）
お前 means ‘you’ but not a polite word. The most common word for you is あなた.
お前 sounds very rough so people do not usually use the word in a conversation. ケンシロウ uses the word to the evil men who harass, annoy and kill decent citizens when he fights them.