New to work ka brother?

According to Employment Act 1955 Section 60D. (Which you had quoted, but not fully.)
Refer to the above bolded parts.
Your company should inform you in two ways regarding the company's public holiday (minimum of 11 days), in the Employment Contract and Internal Memo.

As long as the days are not in the list, you will not be entitled to received holiday pay. If you do work on the days listed in the Holiday List of your company, you will be paid double. If there is OT, triple rate for OT.
For overtime, again refer to your contract for NORMAL WORK HOURS and OVERTIME clause.

If employer explicitly stated no overtime will be paid, then you should not do overtime.

So again, check your contract.