It's a class 2 module so 10 meters/33 feet provided your PC has class 1 or class 2 dongle (if class 3, get a new dongle, range is only 1m but class 3 is rarely used so probably not an issue).

The actual range may vary depending upon environmental factors where the Bluetooth device is used (i.e. walls, other electrical interference etc.)

If 10 meters or 33 feet is an issue for your robot you can upgrade to class 1 bluetooth devices for both the PC and the EZ-B. The class 1 bluetooth has a greater range and may work up to 100 meters or 300 feet.

@robot-doc i don't understand can you give me a youtube link or any thing i want to increase the distance to be more than 10 meters maybe 50 or 100 as you said

You need Class 1 bluetooth both ends if you want up to 100m range.

So you would need a class 1 bluetooth dongle in the PC, this is straight forward enough.

You would also need to replace the bluetooth module on the EZ-B, this is the small board with the red light on which sits over the large IC on the board. Basically it just pulls out. Then you replace it for a UART TTL Class 1 Bluetooth Module.

Search the forum for class 1 bluetooth and you should be welcomed by a few topics which cover this already.

@rich thank you , you got all the answers man great job :)