What does it mean that the page you visit in the boss applet is offline?

It means that the seat is full and can't be delivered any more.

When I am offline, I video or chat online. His house is closed, so I won't video or chat with you. This is called offline. For example, my mother and I are chatting on video. Suddenly there was a phone call to play our video, so I went offline and answered the phone. This means that I am offline. When I'm offline, I close the internet and don't video with you.