How do i make when player touches part then timer starts only for him?

Add a script to the part you want players to touch to begin the timer. Then paste the following code into that script:

local Players = game:GetService("Players")
local teleporter = script.Parent
local debounced = {}

teleporter.Touched:Connect(function(part)
	local player = Players:GetPlayerFromCharacter(part.Parent)
	
	if player and not debounced[player] then
		-- Prevent multiple timers from running for player
		debounced[player] = true
		
		-- Set the location to teleport to
		local target = Vector3.new(0,5,0)
		-- Set the timer duration
		local duration = 5
		
		-- Run the timer on a new thread
		spawn(function()
			-- Run the timer
			local remaining = duration
			while remaining > 0 do
				remaining = remaining - wait()
			end
			
			-- Timer finished, so teleport player
			player.Character.HumanoidRootPart.CFrame = CFrame.new(target)
			
			-- Remove the player from the table
			debounced[player] = nil
		end)
	end
end)

I have added comments to the code for you to walk through and understand. If something isn't clear, then let me know and I can explain.