Translation:My younger sister's face is small.
Chinese often discuss the relative size of someone's face. Small= good = 好看。So, a normal topic of conversation for Chinese speakers.
The audio for this listening exercise is awful. The last 1/3 of the sentence sounds like it's compressed into one word.
Actually yes, I've met many girls complaining that their face was big. I have no idea on which criteria though, they looked perfectly fine... Chinese girls complaining about their appearance (even when there is nothing to complain about) is extremely common, social pressure is huge on them...
Yeah, having a small face is very desirable in China, people do mention it (also noses being straight, ears etc..)