Unlike the pyramid of energy, the pyramid of number represents the number of individuals at each trophic level, per given period and area. The census of the organism in a given habitat is taken to note the number of individuals participating in the food chain.
As the number of individuals decreases at each level, the size of the organism increases (See the below image).
The progressive drop in the total number of individuals at each trophic level is described as a pyramid of numbers.
As the number of lizards decreases from that of grasshoppers, the body size of lizards increases, i.e., the individual organism increases in size from grasshoppers to hawk while their total population/number decreases.