Line 16 is where the problem is
script:
-- Script should be inside the seat
local Seat = script.Parent
local Players = game:GetService("Players")
Seat:GetPropertyChangedSignal("Occupant"):Connect(function()
--Get seat occupant
local humanoid = Seat.Occupant
--Check to make sure seat is not empty
if humanoid == nil then return end
--Get the player sitting in the seat
local occupant = Players:GetPlayerFromCharacter(humanoid.Parent)
--Get that player's seconds from the leaderboard
local Money = Players[occupant].leaderstats.Money
--Increment their seconds on the leaderboard by 1 while sitting
while Seat.Occupant == humanoid do wait(1)
Money.Value += 1
end
end)

3 comments
I told you in the other post how to fix this, replace Players[occupant] with just occupant. The issue is that occupant is already a player object so you don't need to index it from Players.
@Sparks is right.
oh i forgot loll