It is a prevalent hand gesture in the Indian subcontinent. Could mean a lot of things, and interpreted along with the facial expression. In this case, it means

It is a prevalent hand gesture in the Indian subcontinent. Could mean a lot of things, and interpreted along with the facial expression. In this case, it means "That's pretty cool", looking at her facial expressions. It could mean "What the heck is going on?", when accompanied with a different facial expression.