P is play, a time when the trainers and the whales simply play. The trainers act goofy, play with plush Shamus, mirrors, or radio controlled cars, and the whales can join in as much or as little as they want. There is no right or wrong at play time, everybody has fun. Whales are taught new behaviors, and rewarded when they do the right thing. More about learning in a bit.
E is exercise.
Just like our dogs, the whales need exercise. The whole point is to increase the fitness of the animals so they can make it through the activities requested of them. This includes high speed swimming, jumping, and so on. Mike told me of one whale that had been obtained from another marine park who was so out of shape that it couldn't make it around the stadium once at high speed. S is show.