First windows is just a log screen where you can see if a player enters or connects to the server.
"Speler cloetn send to Stijn" means that stijn was in the game when cloetn logged in. So stijn has to be alerted that somebody joined the game and needs to be added on his screen.
Each room has it's own list of player. Overview of who is where in which room.
Just some small traffic analysing to see how much the server has send and received.