What do i need to add or take away to make this script able to end?

I don't know what happened in the process of making your script, but you appear to be missing every end the script needs to have. Normally after typing an if then statement, the Roblox editor gives an end to make typing quicker even though you shouldn't rely on the editor. This should be the script you need:

local tool = script.Parent
local katana = tool.Katana
local db = false 
local backpack = tool.Parent
local player = backpack.Parent
local playerStats = player:FindFirstChild("leaderstats")
local playerSliced = playerStats:FindFirstChild("In Backpack")
local playerSpaces = playerStats:FindFirstChild("Space Available")

local function onTouch(partTouched)
    local canHarvest = partTouched.Parent:FindFirstChild("CanHarvest")
    if canHarvest then
            if canHarvest.Value == true and playerSliced.Value < playerSpaces.Value then
                playerSliced.Value = playerSliced.Value + 1
                canHarvest.Value = false
                partTouched.Transparency = 1 
                partTouched.CanCollide = false
                wait(5)
                canHarvest.Value = true
                partTouched.Transparency = 0 
                partTouched.CanCollide = true
        end
    end
end
local function onTouch(partTouched)
    if canHarvest then
     if canHarvest.Value == true and playerSliced.Value >= playerSpaces.Value then
                script.Parent.Handle.Touched:Connect(function(Hit)
                      local player = game.Players:GetPlayerFromCharacter(Hit.Parent)
                      player.PlayerGui.NES.Frame.Visible = true

                       wait(2)

                       player.PlayerGui.NES.Frame.Visible = false
            end) -- This part needs a parenthesis at the "end" to close the parenthesis past :Connect(
        end
    end
end

This may fix your end issue (I did not test, just put ends where I saw they should be), but you may have a few code errors and issues with how you are handling your task. If this is so, feel free to post another question after **trying **to fix your issue.