He - opposite - him

Him 

1 used as the object of a verb, 

  When did you see him?

after the verb be 

 It's him.

, or after a preposition, 

 He took the children with him

to refer to a male person or animal that has already been mentioned or is easily identified 

Peter is my friend , I love him .

 He 


(used as the subject of a verb) 

1 a male person or animal that has already been mentioned or is easily identified

 Everyone liked my father—he was the perfect gentleman. 

He (= the man we are watching) went through that door.

more info :  http://oaadonline.oxfordlearnersdictionaries.com/dictionary/he