Am/is/are - формы глагола BE (быть) во временах Present
когда говоришь о себе - am ( I am friendly)
когда говоришь мы, они, вы, ты - are ( We are friendly, they are friendly, you are friendly)
когда говоришь он, она, оно - is (She is friendly, he is friendly, it is friendly)
N't или not ставится в отрицательной форме
(She isn't friendly, he isn't friendly, it isn't friendly)