You could say: She’s sitting at one end of the bench. But in order to explain which end, you’d have to add more information. For example: She’s sitting at the window end of the bench
From this:As far as I know, Abcd did not think that. Which post of her did you get that idea from?
By "first seat" I think Abcd means the first row of seats, or the row in the front, closest to the teacher. I agree "first seat" isn't clear.Doesn't"bench"mean chair.