What is the full form of DVD-rw?

What this means is that the device the disk was inserted in is setting up the format of the disk to match the operating system of the device so that it's compatible with the device's recording methods. When it's done recording it'll also most likely finalize the disk' which is to say, close the files so that the disk is properly completed and the files can't be written over until you command the software to erase the disk for re-use.