The meristem is the actual area of cell division in the plant. It is located inside pseudostem on top of the corm at the base of the plant (except when flowering, it travels up the pseudostem and out of the top, producing the flowers and the rest of inflorescence, it ends up in the male bud where it eventually terminates). Other meristems are also located at various points around the corm, when these sprout they form their own pseudostems and these are what become suckers. In many plants, the apical meristem produces a hormone which discourages the growth of too many extra shoots (called "apical dominance"), if you destroy the apical meristem it will break this dominance and allow other shoots to grow out. Many of the buds for new suckers are already formed on the plant, they are just being inhibited until the plant gives them permission to grow.
Here is a diagram taken from Simmonds book, what he labels as "gp" (growth point) is the meristem, as well as the same corresponding area on the sucker.
Simmonds, N.W. Bananas. London: Longmans, 1959.