Here's a breakdown of the sentence:
* Nan: This is the Korean word for "I".
* Mos: This means "cannot" or "couldn't".
* Saeng-gyeoss-eo: This is the past tense of the verb "saeng-gyeo-da", which means "to survive".
So, the whole sentence means "I couldn't survive." This is a very strong statement, implying a difficult or impossible situation. It could be used in various contexts, for example:
* In a metaphorical sense: "I couldn't survive that difficult situation"
* Literally: "I couldn't survive the harsh environment"
The sentence carries a strong emotional weight and suggests a sense of defeat or hopelessness.