The masculine Arabic word for friend is 'sadeeq', and the feminine form is 'sadeeqah'.
If you wanted to say 'he is my friend', you would say 'huwa sadeeqi'. If you wanted to say 'she is my friend', you would say 'heiya sadeeqeti'.

The Arabic form shown below is the masculine form. The femine form just has a 'hah' letter on the end.