is this a global or local variable?

You have just defined the function telling it what to do, but you never called the function. Also yes, it is a global variable. Functions never run automatically, you have to call them your self. Once you tell the function what to do, call it so that it executes.

local function a()
    b = 5
end

a() -- Calls the function

print(b) --prints 5

So local variables are variables that are local to the function. Global Variables are variables that can be used in multiple functions in the script.

So in this example:

local GlobalVariableNameBlah


local function RandomFunctionName()
    local LocalVariableNameBlah
end

GlobalVariableNameBlah is a global variable and can be changed from anywhere in the script. However LocalVariableNameBlah is only alive as long as the function is running. And only things inside that function can access that variable.

So for example:

If I wanted to change the Global Variables value I could do it inside the function. Also note that I could have made it a string or a bool. I just chose an integer.

local GlobalVariableNameBlah


local function RandomFunctionName()
    local LocalVariableNameBlah
    GlobalVariableNameBlah = 20
end

I can't change the Local variable outside of this function in another function. So for example

local GlobalVariableNameBlah


local function RandomFunctionName()
    local LocalVariableNameBlah
    GlobalVariableNameBlah = 20
end

local function OtherFunctionName()
    -- This would be wrong because it only exists in RandomFunctionName
    -- And is deleted as soon as the RandomFunctionName ends.
    -- This would crash it.
    LocalVariableNameBlah = 20 

    -- I can call the global variable though
    GlobalVariableNameBlah = 30
end

It's also important to note that these functions would not run unless I say below them

RandomFunctionName()
OtherFunctionName()

If they were non local functionsI could call them above them like so:

local GlobalVariableNameBlah

RandomFunctionName()
OtherFunctionName()

function RandomFunctionName()
    local LocalVariableNameBlah
    GlobalVariableNameBlah = 20
end

function OtherFunctionName()
    -- This would be wrong because it only exists in RandomFunctionName
    -- And is deleted as soon as the RandomFunctionName ends.
    LocalVariableNameBlah = 20 

    -- I can call the global variable though
    GlobalVariableNameBlah = 30
end

Anything declared inside a function is local yes. Hope this answered your question.