Can't get this script to work. "8:attempt to perform arithmetic (sub) on userdata and number"?

From the looks of things Health is a value holder which would explain your error.

To resolve this you want to access to value indise of Health e.g. Health.Value

local Ore = game.Workspace.Ore.Gold.GoldOre
local Pick = game.StarterPack.Pic
local Health = Ore.Health  -- health is inside ore so just reuse the variable


Ore.Touched:Connect(function(hit)
    if hit.Parent.Name == "Pic" then -- you could also check the health here.
        Health.Value = Health.Value - 10

	-- use <= as multiple touched events may result in a nagative 
        if Health.Value <= 0 then
            Health.Value = 30
            Ore.Transparency = 1 
            Ore.CanCollide = false
            wait(5)
            Ore.Transparency = 0
            Ore.CanCollide = true
	-- should the health be reset here as well?
           end
        end
end)

I am unsure why you need to hold health in a value object. You should be ok having a local veriable for the health.

I hope this helps. Please comment ig you have any other questions about this post.