I can't find the Bug, would somebody help me?

local label = game.Workspace.Cool.SurfaceGui.Frame.TextLabel

game.Players.PlayerAdded:connect(function(Player)

	
	if Players.Player.Name == 'Xianon' then 
		 label.Text = ("Welcome Xianon")
		msg.Text = ("Xianon has entered the game")
		wait (3)
		msg:remove()
		
		
		elseif not Players.Player.Name == 'Xianon' then
			game.Players.Player.Backpack.BT:Destroy()
	end

			
	
	
	if Players.Player.Name == 'ApolloTalentz' then
		label.Text = ("Welcome Apollo")
		msg.Text = ("Apollo has entered the game")
		wait(3)
		msg:remove()
		
		elseif not Players.Player.Name == 'ApolloTalentz' then
			game.Players.Player.Backpack.BT:Destroy()
	end
end)

Two problems with this code.

First, msg is nil. You never created a message.

Second, you keep puttingPlayers.Player.Name.

Although you can do Workspace like that, with all other services you must do either game.SERVICENAME or game:GetService("SERVICENAME").

But here, you don't need to do even that. Since the PlayerAdded event has the built in parameter player, you can just put Player.Name.

Hope I helped!

First, we should look at this expression from line 06:

Players.Player.Name

First, note that Players is not defined for you. Either you must state Players = game.Players or just use the name game.Players explicitly like you do elsewhere in this script.

The period operation is just "syntactic sugar" for table indexing with a string, that is, the above expression is equivalent to this one:

Players["Player"].Name

Note that the purpose of the text Player here, then is not a variable. It is a string, which means the variable Player will be ignored.

If Player were a string value, we would use the explicit table-access syntax with [ and ]:

Players[Player].Name

Though, if this were the case, that would also be redundant, since clearly Player is the object's name.

However, Player is NOT a string. It is a player object, that is, it is that object you are attempting to reference with the incorrect Players.Player. That means you just use Player.Name:

if Player.Name == 'Xianon' then -- Revised line 06

The second issue is that you refer to msg several times, but never define it. You need to create that msg object before you start doing things to it.