"Aamir is our friend."
Translation:आमिर हमारा दोस्त है।
You decide between हमारा and हमारे by looking at the word following it. It should be हमारा if the word is masculine singular, हमारे if it is masculine plural and हमारी if it's feminine. हमारा/हमारे/हमारी all mean 'our' because हम is 'we'.
हमारा कुत्ता - 'Our dog' (कुत्ता is masculine)
हमारे कुत्ते - 'Our dogs'
हमारी बिल्ली -'Our cat' (बिल्ली is feminine)