BLE and HEXA (ServiceUUID and CaracteristicUUID)

Hi folks,
I need to connect Kodular with a BLE device.
I am alread connecting!
I have to send to the device some HEXA code to receive the answer.

I don´t know what is ServiceUUID and CaracteristicUUID!!!
The manifactory say that ServiceUUID is FFB0 and Characteristic is FFB2

Please, someone can help me to understand that?

Thanks a lot