Hi Pp2020
Just to add to what others have mentioned.... While UAN number is unique number assigned to an individuals registered with PF, process to initiate transfer of amount stays same to the extend that if your previous employer was registered with govt. PF fund commissioning authorities, you need to fill form 10C for applying for transfer of funds from previous to current employer.
As every thing in online these days, you will be able to fill in the form 10c online if your previous employer has got it's online registration completed and have their digital signature uploaded.
This online provision is not applicable if your previous employer had their own PF trust (and not with govt. body).
Hope this clarifies further.
Regards!