Probably just intuitive. Intuition is a real thing and the more you listen to it, the stronger it gets sometimes to the point of knowing/seeing things very clearly before they happen.
I think most people don’t realise this about themselves but everyones intuitive, just at different levels and you can easily hone it. Highly recommended.
That being said, a lot of Sana’s predictions are things she could have had an idea about before entering, like Himanshi’s entry. Even GG’s entry coz she’s spoken about him so much, it did make sense for them to bring him at least once.
Also, I’m sure she has mentioned his brother multiple times so some credit goes to the editors too. They’ll put more scenes of her talking about him now coz it’s like a build up to the final entry.
But yeah, she’s definitely more intuitive than the average person.