With Acer Aspire One Notebooks what does the bluetooth module do? Is it the

bt is a device to connect other device or pc or phone or printer.i mean which device's has bt.

Bluetooth is not 3G. It's for connecting to other bluetooth devices. Most commonly for a computer, that would be a wireless mouse. Some printers allow you to connect wirelessly with bluetooth. I had a friend who once connected his wireless cell phone ear piece hands-free thing to his laptop with bluetooth for talking on Skype.