Translation:Your son's nose is pointy and big.
Form Wiktionary; 高鼻子 is a slang term usually referring to a Caucasian person's nose, which compared to the more flattened nose of most Asians, could be said to be "pointy" or "high bridged". If you imagine someone laying down, looking at their face in profile, you can see where the idea of a "high/ tall nose" is coming from.
It is said this way in Chinese, but it barely translates to english, if for no other reason than it's something that just wouldnt be said or even thought. But also because these are not really attributes which we make a note of. Well... big, straight, ski-jump, flat, yes, but high or pointy, no. Conclusion: use the sentence in a different kind of exercise. Translating it is pointless and confusing.
I'm so GRATEFUL for this wonderful FREE course that I hesitate to criticise it in any way, but I totally agree with what you say. It drives me mad! That and the precise English translations. I wrote 'my favourite colour' and was marked wrong. It should have been 'the colour I like best'!! Aaaaaargh ......
When I lived in Taiwan many years ago, little kids would point at us (American whites) and call us "Russian big noses!" (E guo da bizi) in which the "da" referred to the fact that our noses were not like Chinese noses, that is, ours were high bridged, not necessarily "big." I remember crouching down by the kids, pointing at my nose (which is relatively small) and asking them "Is my nose big?" They inspected me carefully and concluded "No, not big." It was a lot of fun.
I never really know what they mean when they say a nose has a high bridge. Does it mean their nose starts higher up on their face or their nose is like a beak and sticks out in the middle? Since photography came in the words used to describe people's appearance have mostly fallen out of general use. When reading all the descriptive terms in 18th century novels I often have no idea what they actually mean.