Connect is not a valid member of BindableEvent?

script.Parent.Touched:connect(function(hit)

if hit.Parent:FindFirstChild("Humanoid") then
	local player = game.Players:GetPlayerFromCharacter(hit.Parent)

	game.ReplicatedStorage.BindableEvents.Sell:Fire(player)
end

end)

The issue is not inside of the script that you provided.

Make sure that inside of your other script where you're receiving this event, it looks like this:

game.ReplicatedStorage.BindableEvents.Sell.Event:Connect(function(player)
	-- Code
end)

The issue would be that you forgot the .Event.

Also, make sure to capitalise the 'C' in Connect, as lowercase connect is deprecated.