On the one hand, it would be nice if you could identify a trusted adult male in his life who could be a mentor about this.
On the other hand, you can contribute something that men can't as effectively -- you can explain how girls and women react to male behavior. He could probably use some advice in order for him to not start on the path that so many "boys" (including middle aged men) on the internet have taken.
A young man needs to know that a lot of behaviors and comments that seem to come naturally are actually going to be offensive. He needs to know that sexual behavior has emotional consequences. He needs to know why so many women and girls are afraid to walk alone at night, and you can encourage him to be a compassionate young man as far as his attitudes toward young women are concerned.
And you can tell him that an obsession with internet porn will create neural pathways that might make it difficult for him to engage in a healthy, loving sexual relationship later on. (I am not saying "no porn". But the type of porn, and the frequency, can be issues. I submit SW as evidence.)
