If you have caught the sun, the sun has made your skin a slightly darker brown or red colour.

You've caught the sun on the back of your neck. 你脖子后面晒黑了。

You've caught the sun on your nose.

I'm feeling a bit sore where I caught the sun.

She's caught the sun on the back of her legs.

You've caught the sun on your shoulders and they're starting to look a bit pink.

See also: catch verb (BE TOUCHED BY)