Here are some Korean counters.  Counters are words like “piece of paper” or “year’s old” that you attach to numbers to indicate sets or numbers of items/people/animals, etc.

별 : items of clothing

대 : vehicles, cars, machinery

과 : lessons

권 : volumes of books

장 : piece of paper

마리 : animals

병 : bottles (alcohol)

잔 : glasses/cups (water or non-bottled liquid)

층 : floors

곡 : songs

마디 : words, phrases

통 : containers, buckets

사람 : people (informal)

분 : people (formal)

Of course there are more counters that I haven’t listed, but these are one of the most commonly used.