For365 also called Good till triggered, is a feature that allows you to create trigger conditions that will execute your buying and selling orders at a price favourable to you. These pre-set orders are valid for 365 days. Once the trigger conditions are met, your order is accordingly sent to the exchange for execution. Then that order would be valid for that day.
In case of FnO contracts, it is valid for 365 days or till contract expiry whichever is earlier.