In Korean grammar, nouns can be classified as countable or uncountable. Countable nouns are those that have a specific quantity and can be counted, while uncountable nouns refer to things that cannot be counted or do not have a specific quantity. To distinguish between countable and uncountable nouns, the Korean language uses different particles and counting words. Mastering the usage of countable and uncountable nouns is essential for improving your Korean grammar skills and overall communication.