I have made a leaderboard script but my level wont show up?

Server Script in ServerScriptService

local DataStore = game:GetService("DataStoreService")
local stats = DataStore:GetDataStore("LevelSaveSystem")

game.Players.PlayerAdded:Connect(function(player)
	local leaderstats = Instance.new("Folder", player)
	leaderstats.Name = "leaderstats"

	local Level = Instance.new("IntValue", leaderstats)
	Level.Name = "Level"
	Level.Value = 1

	local XP = Instance.new("IntValue", leaderstats)
	XP.Name = "XP"
	XP.Value = 0

	local LoadArray = stats:GetAsync(player.UserId)
	if LoadArray then
		player.leaderstats.Level.Value = LoadArray[1]
		player.leaderstats.XP.Value = LoadArray[2]
	end

	if player.leaderstats.Level.Value > 100 then
		player.leaderstats.Level.Value = 100
	end
end)

game.Players.PlayerRemoving:Connect(function(player)
	local SaveArray = {player.leaderstats.Level.Value, player.leaderstats.XP.Value}
	stats:SetAsync(player.UserId, SaveArray)
end)

game.ReplicatedStorage.RemoteEvent.OnServerEvent:Connect(function(player, XP, Level)
	if XP >= Level * 50 then
		player.leaderstats.XP.Value = 0
		player.leaderstats.Level.Value = Level + 1
	end
end)

So your GetAsyncs are a bit messy, so I reworked the script so the two values (Level and XP) are both saved to a single table (this way you only need one DataStore)

The other problem with that from before is that you called the changed events inside the player added event (but they were not localized), the above method circumvents this.

Since the Datastore calls the DataStore's Value first in your scenario, without checking if its nil, the level will stay at the defualt intvalue of 0, which is why I set the value when defining it, as well as the XP and Level values are different from the outset.

Your function pertaining to "XP Changed" looks like an incomplete remote event to me, which means that you would be giving values to the function, but they would have no corresponding property (.Value). If not, you can rewrite it as before. (In this example, I had a Remote Event named "Remote Event" within Replicated Storage)