Specific to the role is about the fitness needed to perform your characters action, running, jumping, climbing, fighting, riding, swimming you name it an actor has to be obtain the fitness levels needed to portray a characters ability to be in the physical. It is important to also identify any risk of injury to further reduce the impact a characters physical ability may have, every actor will knows they have to be physically able to perform the same actions, take after take after take!
Relates to the physical characteristics of your characters look, size, posture frame, overall shape etc, which all help define a believable performance. Sometimes the director will have input to specifics on a characters look from behind the lens, or he may require an actor to have the ability to deliver lines while performing breath challenging scenes, who knows everything and anything could be asked from an actor, and the show must go on, being fit for the part and able to take on any challenge a character demands is all part of the work, and sometimes can be an audition deal breaker.
As an actor you are called upon to perform in costumes, often these can be cumbersome and heavy, maintaining your characters physical poise in full costume for hours at a time is paramount.