like i read your book and then you read one of mine. When someone asks you to do a swap with them they are asking if you will read their book and then they will read yours and then you both will give feed back on what you thought of each others. it’s a good way of getting tips on how to make your writing better and then a good way of finding interesting books that you probably wouldn’t have read. More then that its just a fun thing to do if you like to read and write..