There is no error.
local DSService = game:GetService('DataStoreService'):GetDataStore('Hamburger223232')
game.Players.PlayerAdded:connect(function(plr)
-- Define variables
local uniquekey = 'id-'..plr.userId
local leaderstats = Instance.new('IntValue', plr)
local savevalue = Instance.new('IntValue')
leaderstats.Name = 'leaderstats'
savevalue.Parent = leaderstats
savevalue.Name = 'Tokens'
-- GetAsync
local GetSaved = DSService:GetAsync(uniquekey)
if GetSaved then
savevalue.Value = GetSaved[1]
else
local NumbersForSaving = {savevalue.Value}
DSService:SetAsync(uniquekey, NumbersForSaving)
end
end)
game.Players.PlayerRemoving:connect(function(plr)
local uniquekey = 'id-'..plr.userId
local Savetable = {plr.leaderstats.Tokens.Value}
local sword1 = plr.Backpack:FindFirstChild("Venomshank")
local sword2 = plr.Backpack:FindFirstChild("Firebrand")
local sword3 = plr.Backpack:FindFirstChild("Windforce")
if sword1 then
Savetable = Savetable+50
end
if sword2 then
Savetable = Savetable + 100
end
if sword3 then
Savetalbe = Savetable + 150
end
DSService:SetAsync(uniquekey, Savetable)
end)

3 comments
You aren't giving much of an explanation. The only error I see looking directly at it is you attempting to add 50,100, and 150 directly to a table instance.
Why are you saving different things with the same key? and "Savetable = Savetable+50" will error as its a table.
You also don't need to create a table. You can make it a regular integer.