local Players = game:GetService("Players") -- States a variable for ease. Use GetService!

local SecurityCheck = { -- Lists the rank Security for table SecurityCheck.
   [6 | Security] = true;
}

local HRCheck = { -- Lists all high ranks that will get you banned for table HRCheck.
   [8 | Head of Security] = true;
   [9 | Head of Services] = true;
   [10 | Head Receptionist] = true;
   [11 | Management] = true;
   [12 | Senior Management] = true;
   [14 | Shift Manager] = true;
   [15 | General Manager] = true;
   [16 | Board of Directors] = true;
   [17 | Vice Chairman] = true;
   [18 | Chairman] = true;
}

function CreateNotification(Title)

local Notification = Instance.new("ScreenGui")
local Frame = Instance.new("Frame")
local TextLabel = Instance.new("TextLabel")

Notification.Name = "Notification"
Notification.Parent = game.CoreGui

Frame.Parent = Notification
Frame.BackgroundColor3 = Color3.new(42/255 42/255 42/255)
Frame.BackgroundTransparency = 0.2
Frame.BorderSizePixel = 0
Frame.Position = UDim2.new(0 0 -0.1 0)
Frame.Size = UDim2.new(1 0 0.0183374081 30)

TextLabel.Parent = Frame
TextLabel.BackgroundColor3 = Color3.new(1 1 1)
TextLabel.BackgroundTransparency = 1
TextLabel.Position = UDim2.new(0.31437701 0 0 0)
TextLabel.Size = UDim2.new(0.370607018 0 1 0)
TextLabel.Font = Enum.Font.SourceSansLight
TextLabel.Text = Title
TextLabel.TextColor3 = Color3.new(0.905882 0.905882 0.905882)
TextLabel.TextSize = 30

Frame:TweenPosition(UDim2.new(0 0 0 0) "In" "Linear" .2)
wait(2.2)
Frame:TweenPosition(UDim2.new(0 0 -.1 0) "Out" "Quad" .2)
wait(.2)
Notification:Destroy()
end

function onPlayerAdded(player) -- OnPlayerAdded is the function name. player is referred to what changes.
if SecurityCheck[player:WaitForChild("leaderstats" 3).Rank.Value] then -- If the table matches then..
CreateNotification(tostring(player).. " has joined. Rank: Security")
wait()
end
if HRCheck[player:WaitForChild("leaderstats" 3).Rank.Value] then -- If the table matches then..
CreateNotification("WARNING!".. tostring(player).. "has joined." "Rank: ".. player:WaitForChild("leaderstats" 3).Rank.Value)
wait(1)
end
end

--When a player joins call the onPlayerAdded function
Players.PlayerAdded:connect(onPlayerAdded)

--Call onPlayerAdded for each player already in the game
for _player in pairs(Players:GetPlayers()) do
    onPlayerAdded(player)
end