Explain why an energy pyramid in any ecosystem typically is limited to four or five levels only

Because there is only a finite amount of energy. Energy is lost between each trophic stage. The top predator would gain the least amount of energy, shared between the least amount of organisms within the predator species. Typically there just aren't any other animals that can kill and eat the top predator, but there also wouldn't be enough of the top predator to eat so any species above them would quickly die out.