This button allow you to quickly select all verses.
Press the button once again to quickly clear all selection.
You can select only some of the verses.
You can press "Copy" button to copy the selected verses to the clipboard of your device. You can then "paste" the content into other applications.
Or, you can press "Share" button to share the selected content directly.
In this example, the selected content is shared with an email app. Content is automatically loaded in the email app.