I’m not sure I understand the question, are you asking whether modules can call functions within themselves? If so, then yes:
local module = {}
function module:function1()
self:function2() -- or you could type module:function2()
end
function module:function2()
print("Second function")
end
return module
The purpose of module scripts isn’t simply to “easily change code”, modules are the key to writing code cleanly and clearly though Object Oriented Programming. I’d recommend reading this tutorial: All about Object Oriented Programming