When you rearrange something, you change its position or reorganize its contents. You could rearrange your bookshelves so that the books are sorted by color, rather than by title or author.
After riding in a car with the windows down, you might need to rearrange your scarf and hairdo. And, if you're making room in your apartment for a friend to stay over, you might want to rearrange your furniture to accommodate an air mattress. You can also rearrange a schedule or routine. This word adds the "back or again" prefix, re-, to arrange, a verb which originally meant "draw up a battle line."