How Can I Implement, Death Resulting In Loss Of Gold And Experience?

I'll explain the code in the script

game.Players.PlayerAdded:connect(function(Player) --When a player joins then do the following code...
    Player.CharacterAdded:wait() --Wait for the character to spawn
    wait(1) --Make sure everything loads
    Player.Character.Humanoid.Died:connect(function() --Once the character is loaded then find the humanoid and wait for it to die. Once it does, do the following code...
        if Player.leaderstats.Gold.Value >= 25 then --If the gold is bigger than or equal to 25 then do the following code...
            Player.leaderstats.Gold.Value = Player.leaderstats.Gold.Value-25 --Subtract 25 from the player's gold
        else --If the gold isn't bigger than or equal to 25 then do the following code...
            Player.leaderstats.Gold.Value = 0 --Make the player's gold 0.
        end --Close the If statement
    end) --Close the died event
end) --Close the PlayerAdded event

Enough detail for you?

Just so you know, this is very close to being against the rules of SH, especially since you didn't post any code to try and do this yourself.

The easiest way to do this is to call a function when the Player dies, giving it the Player and the Enemy that killed them, something like this:

function playerDied(Player, Enemy)
    if not Enemy then return end --Environmental deaths are 'free'
    local levelDifference = getLevel(Player) - getLevel(Enemy)
    if levelDifference <= -10 then return end --No loss for enemies greater than 10 levels above you.
    levelDifference = levelDifference + 10 --Convert this to a completely positive scale.

    setExperience(Player, getExperience(Player) - 10*levelDifference)
    giveGold(Player, -1*levelDifference)
end