South Exit
South Entrance, Southern Exit, Southern Entrance, South Gate
noun
The South mouth isn't actually a mouth you find in the south pole or anything, it's an entrance or exit. This is kind of like how 入り口 means entrance (the 口 represents a doorway). You'll see this word a lot in places like train stations or airports. It means both South exit and South entrance.
The reading for these kanji are both kun'yomi. Probably because it's two words put together (South + Exit) rather than a single word. Also, body parts tend to change words into kun'yomi readings as well. So, you've seen vocab words that give you the kun'yomi reading of both 南 and 口, right? Now you just need to combine the two vocab readings into one to be able to read this word. Just watch out for the rendaku that changes くち to ぐち.
南口から出るとすぐにお茶の店があります。
As soon as you get out of the south exit, there is a tea shop.
来年の夏には南口にコンビニができるらしい。
It seems that there will be a convenience store at the south exit next summer.
南口のベンチは、おばあちゃんとおじいちゃんに人気のデートスポットです。
The bench at the south exit is a popular dating spot for grandmas and grandpas.