Can someone tell me how do I use tables for data saving?

Roblox doesn't save tables in Datastore. It only saves numbers and strings(text).. however, you can encode tables into strings to save in datastore, and then decode them back to a table when you read them from Datastore..

you can make your own encoder/decoder, but the HttpService has functions that encode tables into JSON formatted strings, and from JSON formatted strings into Lua tables..

the 2 functions are HttpService:JSONEncode() and HttpService:JSONDecode()

so here is a basic example:

local HttpService = game:GetService("HttpService");
local DataStoreService = game:GetService("DataStoreService");
local DataStore = DataStoreService:GetDataStore("name of data")

local data  = {
    coins = 200,
    swords = {
        "Katana",
        "Galactic Saber",
        "Special sword"
    },

    guns   = {
        "MP3",
        ".5 Caliber Sniper",
        "M6 machine gun"
    }
}


local stringData = HttpService:JSONEncode(data);
DataStore:SetAsync("key goes here", stringData)

The above should save everything in that table to datastore, the following should read the data and turn it back into a table;

local stringData = DataStore:GetAsync("key goes here") or "{}"
local data = HttpService:JSONDecode(stringData); --back into a table

print(data.guns[1]) -- will print "MP3"

make sure tables are not mixed when using JSONEncode and JSONDecode

which means table shouldn't look like this:

local t = {name = "jack", 1,2,3,4};

instead it should look like this:

local t = {name = "jack", numbers = {1,2,3,4}}

First of all create a server script in serverscriptservice Then turn API services on. So the server knows where to store the data via.

You need to store the data as two variables like this Datastore does not fully function in ROBLOX studio, so do it on ROBLOX itself

local DataStoreService = game:GetService("DataStoreService")
local myDataStore = DataStoreService:GetDataStore("myDataStore")


game.Players.PlayerAdded:Connect(function(player)
 local leaderstats = Instance.new("Folder")
 leaderstats.Name = "leaderstats"
 leaderstats.Parent = player

 local Deaths = Instance.new("IntValue")
 Deaths.Name = "Deaths"
    Deaths.Parent =  leaderstats

local Wins = Instance.new("IntValue")
Wins.Name = "Wins"
Wins.Parent = leaderstats

 local PlayerUserId = "Player_"..player.UserId

 local Data
 local sucess, errormessage = pcall(function()
  local Data = myDataStore:GetAsync(PlayerUserId)
 end)

 if sucess then
  Deaths.Value = Data -- Storing variable
  Wins.Value = Data -- Storing variable

 end



end)

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

 local PlayerUserId = "Player_"..player.UserId

 local Data = {Deaths = player.leaderstats.Deaths.Value, Wins = player.leaderstats.Wins.Value;}

-- We stored the data to two variables above this comment

 local sucess, errormessage = pcall(function()
  myDataStore:SetAsync(PlayerUserId, Data)
 end)

 if sucess then
  print("Data succesfully saved")
 else
  print("Data not saved")
  warn(errormessage)
 end
end)

Please comment if there are any errors