Coin that adds to leaderboard on contact?

Ok. First of all, this is not a request site, so please do not think it is. However, I will help you just this once. So first off you need leaderboards:

game.Players.PlayerAdded:connect(function(plr) -- This line goes off once a player joins the game. That player can be refferred to as 'plr' through this function
	local stats = Instance.new('IntValue',plr) -- leaderstats, children's value desplayed to all players
	stats.Name = 'leaderstats'
	local coins = Instance.new('IntValue', stats)
	coins.Name = 'Coins' -- Chnge 'Coins' to what you want to name to be
	coins.Value = 0 -- Change this to be the Value theyhave when they join
end)

That is a very simple leaderboard script. If you want to save it when they join and leave, I'll update it with explanations of DataSTores. Now, the coin. Lets say you make a part, which is meant to be the coin. You now need a script like this in the part:

local debounce = false
function onTouched(part)
	local h = part.Parent:findFirstChild("Humanoid")
	if (h~=nil) then
		if debounce == false then
			debounce = true
			local thisplr = game.Players:FindFirstChild(h.Parent.Name)
			local stats = thisplr.leaderstats
			local score = stats.Coins-- change this to what the thing is called now, if you changed the name of Coins
			if (score~=nil) then
				local mon = math.random(250,1000) -- Makes a random number
				score.Value = score.Value + mon -- change this to the number of coins they get if you don't want it to be random. You didn't specify what you wanted.
				wait()
				local item = script.Parent
				item:ClearAllChildren()
				item:Destroy()
			end			
		end
	end
end

script.Parent.Touched:connect(onTouched)

The script above is very basic. Once touched by a player, the parent of the script will be removed and the player will receive coins. (In this case, a random number that could be 250-1000) - Now the last part, which is spawning the part. Put the part in Lighting or ReplicatedStorage. Now this script will be in workspace.

local item = game.Lighting.Part -- find the item
while wait(60) do -- change the number to what you want
	local clone = item:Clone()
	clone.Parent = workspace
	-- add a line to choose position if you want to
end

Now, all these scripts are very simple and should be improved. I typed them without opening studio, simply to help you understand the concept. Good luck from here! (I typed this out in 10 minutes while on the site, typos and silly mistakes are bound to happen) Have a great day.