Pressing the menu button brings up additional Bluetooth settings.
This setting controls how long your device will remain visible to other Bluetooth devices when you make it visible under My device. A suitable default value is 2 minutes.
Making your device visible to other devices is only necessary when you want to set up a pairing with a new device, and only when you want to initiate the pairing from the other device. Once two devices are paired, they will continue to be able to see each other. If you are initiating a pair request from this device, you do not need to make it visible, you only need request a pair with the other device by finding it under Available devices.
While your device is "visible" to other, non-paired devices, it is possible for other people to determine where your device is and therefore track your movement, by knowing when your device is within range of an area. For this reason, it is common practice for mobile devices such as smartphones and tablets to always remain "invisible" while Bluetooth is on, except when temporarily enabling visibility if it's needed for pairing.
Security features built into Bluetooth try to ensure your device cannot be uniquely identified when it is not in "visible" mode, even though devices it is already paired with can identify it via special cryptographic means.
Via Bluetooth is it possible for devices to "push" files to other devices, if the receiving device is capable of receiving them and accepts the file. This option takes you to a list of files you have accepted and received from other Bluetooth users using this feature.
This affects the name your device appears as to other devices, while it is "visible", or paired with another device. Choose a name that allows you to recognise your own device in a list of devices, should you need to choose it from a list on another device.