Well I think that what he means is that you dont need to work on .... anything
You can be yourself here and people will say thing to you directly and not be sneaky. Here someone can tell you to fuck off and eat a dick . So if someone is mad at you they will say so and not be sneaky about it.
And the comfort and safety in that is that our friendships are sincere and not forced.
He may not have said anything but I have issues confronting others irl and I believe that trying to approach a somewhat combative attitude could be helpfull on this area and I could learn a few things from it without getting as wounded as I would if it happened irl.
Is it an assertive attitude you are hoping to approach rather than a combative one? An assertive attitude means you confront someone calmly and with respect rather than with raised voices, clenched fists, and threats.
For example, the other day I was in a movie theater with my husband and daughter. The lights had been dimmed and the funny commercial for silencing cell phones and no texting had already played although the movie had not started yet when someone right in front of us started obviously texting on his cell phone. The reason for not texting is that the glow of the screen is distracting to the other people who are trying to watch the movie.
A non-confrontational response would have been to say nothing and hope that the person stopped texting when the movie started. A more combative response would have been to tell the person to stop texting or else I would go get a manager to throw him and his cell phone out of the theater. What I did was to ask the person if he was going to be finished texting by the time the movie started and he finished the text he was working on and put his cell phone away.