"make a lua script executor. Also create the gui for it. Make the gui look good. And put it were all players can see it. attempt to index nil with 'PlayerGui' fix it."

-- server script 
local Executor = script.Parent
local Players = game:GetService("Players")

local function createGui(player)
	local gui = Instance.new("ScreenGui")
	gui.Name = "LuaExecutor"
	gui.Parent = player.PlayerGui
	
	local frame = Instance.new("Frame")
	frame.Name = "MainFrame"
	frame.Size = UDim2.new(0.5, 0, 0.5, 0)
	frame.Position = UDim2.new(0.25, 0, 0.25, 0)
	frame.BackgroundColor3 = Color3.fromRGB(255, 255, 255)
	frame.BorderSizePixel = 0
	frame.Parent = gui
	
	local textLabel = Instance.new("TextLabel")
	textLabel.Name = "TextLabel"
	textLabel.Size = UDim2.new(1, 0, 0.2, 0)
	textLabel.Position = UDim2.new(0, 0, 0, 0)
	textLabel.BackgroundColor3 = Color3.fromRGB(255, 255, 255)
	textLabel.BorderSizePixel = 0
	textLabel.Text = "Enter Lua Code Here:"
	textLabel.TextColor3 = Color3.fromRGB(0, 0, 0)
	textLabel.Parent = frame
	
	local textBox = Instance.new("TextBox")
	textBox.Name = "TextBox"
	textBox.Size = UDim2.new(1, 0, 0.6, 0)
	textBox.Position = UDim2.new(0, 0, 0.2, 0)
	textBox.BackgroundColor3 = Color3.fromRGB(255, 255, 255)
	textBox.BorderSizePixel = 0
	textBox.Text = ""
	textBox.TextColor3 = Color3.fromRGB(0, 0, 0)
	textBox.Parent = frame
	
	local button = Instance.new("TextButton")
	button.Name = "Button"
	button.Size = UDim2.new(1, 0, 0.2, 0)
	button.Position = UDim2.new(0, 0, 0.8, 0)
	button.BackgroundColor3 = Color3.fromRGB(255, 255, 255)
	button.BorderSizePixel = 0
	button.Text = "Execute"
	button.TextColor3 = Color3.fromRGB(0, 0, 0)
	button.Parent = frame
	
	button.MouseButton1Click:Connect(function()
		local code = textBox.Text
		local success, err = pcall(function()
			loadstring(code)()
		end)
		if not success then
			print(err)
		end
	end)
end

Players.PlayerAdded:Connect(function(player)
	createGui(player)
end)