Normally sixty days means two months. In most of the companies they specifically mention in the appoint letter / exit policy / standing orders / employee hand book about the Notice period. Some companies specifically mention that the resigned employee is not eligible to avail any leave during the course of Notice period and even in exigencies he avails the employee need to compensate by working for additional days ie., 60 days is your notice period and you availed leave either with or without pay for 7 days then you need to work for 7 more days.
In general this 60 / 90 days are continuous ie., including the weekly off /holidays falling in between ie almost 2 / 3 months mode of process but not actual working days.
Thanks and regards
4th January 2018 From India, Hyderabad