Die upon losing all your lives script?

First of all add debounce so that the player who touches the brick doesn't lose all their lives when only touching once.

local db = false --Our debounce
function onTouched(hit)
if db == false then
    db = true
    local hitname = tostring(hit.Parent)
    if game.Players:findFirstChild(hitname) then
           local player = game.Players:findFirstChild(hitname)
           local lives = player:findFirstChild("Lives")
           lives.Value = lives.Value - 1
       end
    wait(1) -- Wait 1 second before losing a life again when touched.
    db = false 
    end 
end

script.Parent.Touched:connect(onTouched)

Next we want to kill the player when the player has lost all their lives so we add this:

local db = false --Our debounce
function onTouched(hit)
if db == false then
    db = true
    local hitname = tostring(hit.Parent)
    if game.Players:findFirstChild(hitname) then
           local player = game.Players:findFirstChild(hitname)
           local lives = player:findFirstChild("Lives")
           lives.Value = lives.Value - 1
           if lives.Value <= 0 then --If the player has lost all their lives then..
               hit.Parent.Humanoid.Health = 0 --Kills the player
           end
       end
    wait(1) -- Wait 1 second before losing a life again when touched.
    db = false 
    end 
end

script.Parent.Touched:connect(onTouched)