If they are referring to the type of paint to use on foam, they are simply saying that spray paint will eat away at the foam.(which is not always a bad thing, can add a distressed look which is always cool.) "Latex" paint is simply paint you would use to paint your walls or your house. Cheapest your local store has. I have used "Drylock" brand also which will weather seal whatever you paint. I also use polyurethane spray to seal the project upon completion. Hope this helps and remember, the best way to learn, is to simply try. Good luck!