It’s hard to say for sure because of the stretching, but it looks like the train on the left is stopped at a signal that shouldn’t be there.
Train Fever uses path signals, which should be placed where a train can wait at them without blocking any track. In that screenshot there are six signals, but the only one that looks like it should be there is the top-right one that the incoming train is stopped at.
That signal will keep that train on that branch until there is a clear path to the platform, so it can’t block any track. If the train on the left is trying to head out of the station to the right and is stuck then there must be something off screen at the top preventing it from moving. A path signal reserves a path to the next safe stopping point, which is usually either the next signal or a station. Is there a section of track we can’t see that has a train in it?