An abridged version of your book is simply a shorter version. In audio books it is often better to do an abridged version to keep the book shorter and more entertaining for the listener. An abridged version can also keep the production time shorter, the retail prices lower, and the profit margins higher because the product will be easier to assemble and more entertaining for the listener. Your audio book producer will review this with you before you submit your final version of the manuscript that you want to be used for the production of your audio book. Your editor and the producer will not abridge the book for you, that will be up to you to complete if you desire to do so.