Duration of stay – this is the maximum number of days that the visa holder can remain in the Schengen Area. The day that you enter the Schengen will be counted as “Day 1”, and the day that you leave Schengen will be your “Last Day”.
Do keep in mind that “Day 1” and “Last Day” will be counted on the basis of the date that you enter/exit on. Even if your entry/exit is somewhere around midnight, it will be calculated as per the date.
Visa Validity – This is the period of time during which you can make use of your visa for entering and staying in the Schengen Area.