What is the significance of the fact that the droplets carried different charges?

The charges on a droplet can be used to represent the number of electrons carried by this droplet.

In other words:

a droplet having a charge of 1.60 x 10^-19 has 1.60 x 10^-19 electrons while a droplet having a charge of 3.15 x 10^-19 has 3.15 x 10^-19 electrons.

From the observations:

The fact that the droplets carried different charges signifies the fact the different droplets carried different numbers of electrons