what is "direct final degree in 1,2 sittings from recognized university" ads mean

Degrees are best earned through proper education in recognized institutes. And recognized / reputed institutes do not require to advertise themselves in such a way as is depicted by you in the example. It might not be very authentic. My suggestion is not to get attracted towards such advertisements.

Yes some of such a program is there that is one year direct degree program by distance mode. But only thing is you will not get admission in PG courses. There are restriction for certain PG courses and competitive exams.