Data Store Error [plz help?]

You are trying to find a child in game called DS and there is no such thing. You already defined the variable so, you don't need to get the Parent again.

Change line 2 to:

local CurrencySave = DS:GetService("FirstStore")

WAIT!!

We're not done. Another error on line 2 is that you are saying :GetService(). This can only be done on game. You are trying to get a service in a service. It just doesn't make sense.

It should be:

local CurrencySave = game.DS:GetDataStore("FirstStore")

We're still not done.

You just added the IntValue Cash in the leaderstatsbut, on line 31, you said:

player.leaderstats.Fruit.Value

I think what you meant was:

player.leaderstats.Cash.Value

If it wasn't what you were trying to do, then please let me know.

Okay, that's it, sir!

I hope this works and make sure to accept this answer if it does!

If it doesn't, then please tell me what errors you are getting in the output.

This code is destined to work.

local DS = game:GetService("DataStoreService")
local CurrencySave = DS:GetDataStore("FirstStore")


game.Players.PlayerAdded:Connect(function(player)

    local leaderstats = Instance.new("Folder", player)
    leaderstats.Name = "leaderstats"
    leaderstats.Parent = player

    local cash = Instance.new("IntValue", leaderstats)
    cash.Name = "Fruit"
    cash.Value = 100

    local data
    local success, errormessage = pcall(function(player)
           data:GetAsync(player.UserId.."-cash")
    end)

    if success then
        cash.Value = data
    else
        print("There was an error while getting your data")
        warn(errormessage)
    end
end)

game.Players.PlayerRemoving:Connect(function(player)

    local success, errormessage = pcall (function()
    CurrencySave:SetAsync(player.UserId.."-cash", player.leaderstats.Fruit.Value)
    end)

    if success then
        print("Player data Saved!")
    else
        print("Player Data didn't Save.")
        warn(errormessage)
    end

end)