Hebrew question
הוא סיפר לי על החברות שלו טובות
what does it mean?
Is mean that he told me about his good friends? or is mean that he told me good words about his friends?

Question

Answer

It looks to me that you got the sentence a bit wrong - they way it is, it isn't correct:
he spoke good things about his (girl)friends-----הוא דיבר טובות על החברות שלו

if you want to use the verb told - he told me good things about his girlfriends it would be:
הוא סיפר לי דברים טובים על החברות שלו

and to say: he told me about his good girlfriends, it would be:
הוא סיפר לי על החברות הטובות שלו