What/how does delay() mean/it apply in ROBLOX Lua Scripting blah blah blah?

delay only exists in roblox, it's a function that runs given function in another thread after a given time, example like this

local function DoSomething()
	
	print('Hello')
end

delay(10, DoSomething)

This will print "Hello" after 10 seconds, the function itself looks like this

local function delay(Time, Function)
	
	coroutine.wrap(function()

		wait(Time)

		Function()
	end)()
end

You see it does not stop the thread at all, it creates a new coroutine which spawns new thread instantly. Just like wait, Time before executing function must be higher than 1/30, if it's lower, it will automatically be 1/30. In cases where you don't want to stop the thread, you can use delay instead of that.

local Part = Instance.new('Part', workspace)
local Part2 = Instance.new('Part', workspace)

delay(3, function()

	Part.Color = Color3.fromHSV(0.5 , 1, 1)
end)

Part2.Color = Color3.new(1, 1, 0)

wait(2)

print(Part2.Color)
print(Part.Color)

wait(2)

print(Part.Color)

> Output:

-- 255, 255, 0
-- 151, 153, 152 (Or whatever the default part color is)
-- 126, 255, 255

Delay is the function at the top here, you can read about it.