What is the meaning of 여인?

woman, lady

Sino-Korean 남자(男子) (namja, “boy; guy; man”) and 여자(女子) (yeoja, “girl; woman”) are the most common words, but can have a somewhat informal connotation.

Sino-Korean 남성(男性) (namseong, “male; men”) and 여성(女性) (yeoseong, “female; women”) refer to men and women as groups—though pluralized 남자들 (namja-deul, “the boys; the guys; the men”) and 여자들 (yeoja-deul, “the girls; the women”) is informally more common for this purpose—or to individual adult men and women in formal or polite contexts.

Sino-Korean 여인(女人) (yeoin, “woman”) is literary. There is no male counterpart.

The bare Sino-Korean morphemes 남(男) (nam, “male”) and 여(女) (yeo, “female”) are generally used in formal contexts, especially when referring to each gender as a collective but also for male or female individuals in more legalistic contexts. They are commonly written in hanja even when the rest of the text is in pure Hangul script.

Native 사내 (sanae, “man”) and 계집 (gyejip, “woman”) are not as commonly used. 사내 (sanae) often has a connotation of machismo or manliness, while 계집 (gyejip) has become offensive and derogatory.

Source: wiktionary.org