“Validity of the visa” means the date of first possible entry and the latest date your should depart from the Schengen States.
Where do I find the duration of validity on the visa sticker?
If you look at the visa sticker in line 2 ‘from … to’ this is the validity of the visa.
How or where do I find the permitted duration of stay in the visa sticker?
If you look in line 3 under ‘duration of stay’ you will find a number. This is the duration of the legal stay with this visa in the Schengen States.