He means that you only need to tanker enough fuel to cover the fuel for the next sector immediately after the 'tankering' sector ie tanker on leg 1, but only tanker enough fuel to be able to meet leg 2's requirements even though you may have additional capacity to carry more. No use carrying more fuel than will be needed.
Bear in mind the advice others have given: Tankering to cover leg 2 but finding you landed after leg 1 with not quite enough fuel for leg 2 can be expensive due minimum fuel purchase requirements.
Another option, if you don't have sufficient capacity to tanker for the whole of leg 2 *and* have min. purchase requirements at the intermediate landing point, is to plan to arrive from the tankering leg needing just the min. fuel purchase amount for leg 2. I've done that plenty of times in the pistons & turboprops I fly.