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 one day for every 20 days, I would like to state that it is for eligibility that we take 240 service days. That will include all weekly holidays, holidays, and leave with pay days. It shall also include layoff days and days on which the employee was absent due to employment injury. However, for these weekly off days, holidays, etc., the employee will not earn leaves. This means, for counting the number of days' leave one has earned, only the days he is physically present will be taken into account. Please see the explanation 1 to section 79 as follows:
Explanation 1: For the purpose of this sub-section— (a) any days of layoff, 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.