I dunno at what school this photo was taken, but in my day, it was not uncommon for students in dorms to have a mini whiteboard on their door so people could leave a message. Mind you, I went to school before everybody had iPhones.
What I believe we’re looking at here is a photo of somebody’s (presumably Joseph Silva’s) door with a mini whiteboard and someone’s (again presumably Joseph Silva’s) contact info, which happens to be a Lemmy user.
The key word here is Lemmy, which would explain why OP shared this photo on !fediverse.