This is the picture posted as the default profile picture on any social media website, i.e. Facebook, Twitter, Tumblr etc., that is a picture of a "bro" with his shirt off flexing in the mirror, or flexing on the beach.
"I just uploaded my new brofile pic, check out how big my muscles look in the mirror."
"Take a picture of me on the beach so I can set it as my brofile pic to show off my abs."
"Eh breh, it's time to hit the gym to get that brofile pic for the ladies."
A picture of one of your male friends or brothers on your profile picture.
I added a brofile pic of one of my brothers on my profile pic on facebook page.