Do I have to pay any compensation to the employer if I resign in probation?

Hello Sir

How can I count my probation period?

I joined the company on Nov 22 and the company gave me an offer letter on 15 Dec.

Which date will be counted for my 6 month probation period as per the UAE law?

Can I resign before the 6 months of probation or after 6 months?

Do I have to give any visa costs to the company when I finish my 6 months probation period?