Device transfer allows you to transfer files from your iPhone library to another paired iPhone using either bluetooth or wifi without the need to connect to the internet. Very good for sharing photos and videos.
Note: both devices should be on the same app and make sure both devices have bluetooth turned on.
To pair: press above "browse devices" and choose the iPhone you want to transfer file to and pair. Then choose documents, images and videos from your library and send them. On the receiving device the received files will be automatically be stored in the device's library.