Sorry, it is section 79. Please read the explanation 2 to section 79 as follows:
Explanation 2.—The leave admissible under this sub-section shall be exclusive of all holidays whether occurring during or at either end of the period of leave.
Now regarding the on day for every 20 days, I would like to state that it is for eligibility that we take 240 service. That will include all weekly holidays, holidays and leave with pay days. It shall also include lay off days, days on which the employee was absent due to employment injury. But for these weekly off days, holidays etc, the employee will not earn leaves. That means, for counting the number of days' leave one has earned, the days he has physically present only will be taken. Please see the explanation 1 to section 79 as follows:
Explanation 1.—For the purpose of this sub-section— (a) any days of lay off, by agreement or contract or as permissible under the standing orders; (b) in the case of a female worker, maternity leave for any number of days not exceeding twelve weeks; and (c) the leave earned in the year prior to that in which the leave is enjoyed, shall be deemed to be days on which the worker has worked in a factory for the purpose of computation of the period of 240 days or more, but he shall not earn leave for these days.
Please see the last words,,,,, " but he shall not earn leave for these days".
Hope it clarifies your doubt.