How can I make a leaderboard that saves your amount of kills?

We need to:

• Get the Player
• Setup the initial leader stat value
• When changed, update it in the data store

-- Create / Get a Data Store for Player Kills
local DataStore = game:GetService("DataStoreService"):GetDataStore("PlayerKills")

-- Save a number
function SaveNumber(userid, ammount)
-- We would normally use UpdateAsync but in this case due it is per-player data we can also use SetAsync
DataStore:SetAsync(tostring(userid), ammount)
end

--Setup leaderstats
function create_stats(player)
    if player:FindFirstChild("leaderstats") then
        player.leaderstats:Destroy()
    end
    local mod = Instance.new("Model", player)
    mod.Name = "leaderstats"
    local kills = Instance.new("NumberValue", mod)
    kills.Name = "Kills"
    kills.Value = DataStore:GetAsync(tostring(userid)) or 0
    return kills
end

-- Do this when a player joins
game.Players.PlayerAdded:connect(function(player)
    local kill_value = create_stats(player)
    kill_value.Changed:connect(function(NewValue)
        SaveNumber(player.userId, NewValue)
    end)

Note: This is a server script.

Please comment if you don't understand something.