"Extra rinse" refers to an additional cycle of washing clothes that helps to make them cleaner and remove any remaining detergent or residue. Full definition
My little guy has always turned a bit pink where he touches cloth diapers (even though we always buy organic and do extra rinse cycles after washing) I use these liners at nap time and he is not red anymore. (littlespruceorganics.com)
Or run a wash cycle with RLR and then do extra rinses to make sure that it's rinsed clean. (clothdiaperaddicts.com)