In this quotation from chapter 4, the narrator is describing the beauty of animals in zoos acting in a "leisurely way." In short, the quote describes the limitations of our human language in regards to description.
Pi describes the beauty of animal activity at two specific times of day: sunrise and sunset. He says that those are the two times that folks should visit zoos.
Pi first talks about having to hurry by the animals at their awakening, at sunrise. This is because he is on his way to school. At this time of the day he doesn't have enough time to linger, but can only catch a glimpse of what the animals are doing.
It is AFTER school when Pi can really grasp the animals "perfection." This is where your quote comes in. I would like to include the context for you:
It was after school that I discovered in a leisurely way what it's like to have an elephant search your clothes in the friendly hope of finding a hidden nut, or an orang-utan pick through your hair for tick snacks, its wheeze of disappointment at what an empty pantry your head is. I wish I could convey the perfection of a seal slipping into water or a spider monkey swinging from point to point or a lion merely turning its head. But language founders in such seas. Better to picture it in your head if you want to feel it.