Basically, it's any product that Japan or Vietnam would import. If you think about it, they have high tariffs, and without an agreement there's no way to police what tariffs they would put on it. They can put whatever they want, as there would be no countervailing issues with it. If you think about pork, soybeans, anything that you can think of that would go into Japan would benefit from the TPP, because there would be an agreement to go against if they wanted to increase the tariffs.
On May 12th, 2016. See this statement in context.