[Seerah]

As stated above, k and v are just regular old variables. You could use anything else in their place. This is what has been done with your example. Instead of doing

for k, v in pairs(self.pluginConstructors) do

They did

for name, constructor in pairs(self.pluginConstructors) do

Since constructor turns out to be a function that they can call later in that statement,

local plugin = constructor()

I assume that the table self.pluginConstructors is structured like this:

self.pluginConstructors = {
     pluginName1 = constructorFunction1,
     pluginName2 = constructorFunction2,
     pluginName3 = constructorFunction3,
}