Chat users which do not fall into the concurrent connections limit (for example if you have a 5 concurrent chat limit and you're already talking to 5 people), get added to a queue, and they'll see a message in their chat box saying, "You are X in the queue" (where X is the number they are in the queue to be connected to an agent).

As soon as an active chat has completed, the chat queue is adjusted, the chatbox in position 1 will be added into Boxcar for you to connect to, and the chatboxes still in the queue will increment their displayed position as well.