How would I make a .Touched Event hit multiple players at once?

Okay, so I will explain how I would do it. You mentioned tables in the comments, and I think thats a very great approach. You're off to a good start.

First, I would use the part.Touched event. Then, I would want to check if they are a valid character FindFirstChild("Humanoid") and then check if they're already in the table or not. I wrote a function that basically just loops through a given table and returns true if the value inserted in the argument is in that table. If the if-statement passes, that means that the player who touched it ISNT in the table, so we accordingly add them. Then, we do damage, wait for a cooldown, and then remove them. Just like a debounce.

--Psudar
--Sep 1 2019
--ServerScript

--//Instances

--script is parented to the part
local Part = script.Parent

--Variables

local COOL_DOWN = 5

--//Functions

--this func checks if a value is in a table
local function FindEntry(tbl, val) 
    for iteration, value in pairs (tbl) do
        if value == val then
            --if found, return true
            return true 
        end
    end
end

--this is the table we're gonna store players in
local TouchedPlayers = {} 
--t == touched or hit, just shortened it
local function onTouched(t)
    --check if its a player and if they're not in the table
    if t.Parent:FindFirstChild("Humanoid") and not FindEntry(TouchedPlayers, t.Parent) then 
        --if they aren't, put the character in the table
        --add them into the table at the most recent entry, +1
        table.insert(TouchedPlayers, #TouchedPlayers + 1, t.Parent) 
        --do damage to the player
        t.Parent.Humanoid:TakeDamage(25) 
        wait(COOL_DOWN)
        --removes the most recent entry (would be our player)
        table.remove(TouchedPlayers, #TouchedPlayers)
    end
end

--//Connections

--connect function on touched 
Part.Touched:Connect(onTouched)

Hope this helps, if you have any questions, leave a comment!

its really easy tbh

basically it changes the players name to hit and if the player got hit then the script says no dont hit agian

local deb = false
Part.Touched:Connect(function(hit)
    if not deb then
        if hit.Parent:FindFirstChild("Humanoid") and game:GetService("Players"):GetPlayerFromCharacter(hit.Parent) then
            deb = true
            local targetPlayer = game:GetService("Players"):GetPlayerFromCharacter(hit.Parent)
            local targetCharacter = targetPlayer.Character
if not targetCharacter.Name == "hit" then
            local targetHumanoid = targetCharacter.Humanoid
            target.Character.Name = "hit"
            targetHumanoid:TakeDamage(25)
        end
        deb = false
    end
end)