Can someone help me understand what is returning, a good example?

Returning is used to send informations back to where the function is called, here is an example:

local function sayHi()
    return "Hi!"
end
-- Print returned value of sayHi
local returnedValue = sayHi()
print(returnedValue)

Here is the expected output:

Hi!

You can also return using integers, as well as performing arithmetics.

local function multiply(x, y)
    return x*y
end

local returnedValue = multiply(5, 5)
print(returnedValue)

25

Returning is very simple and easy to learn and very useful.

You don't have to wrap in a variable print(multiply(5, 5))

Quick Recap: Returning is used to send informations to where the function is called, so whatever your returned value is, that value will get sent.

There's a really good Lua documentation page for exactly what you're looking for. https://www.lua.org/pil/4.4.html