Only applies to an Android app.
When your app attempts an out-of-band authentication, the user sees an additional view on their second device. This view is called "oob_notification_view" and you can replace the "strings" it displays.
Inside the top level "views" object, find the "oob_notification_view" object.
"views":{
"oob_notification_view":{
"strings":{
"oob_notification_title":"Sign-in",
"oob_notification_message":"Click to open the notification"
}
}
}