"Whatever you want to say, all day, until night folds up and files it away" is a second stanza from <em>the Metaphor</em>, a poem written by Eve Merriam. The poem explores the theme of temporariness of all the things, and expresses hope for the future. What the author was trying to convey in this line is that everything we say (or do) goes away at the end of the day. Each new day is a new beginning, a new chance for each one of us to start over.
