Koreans use it when introducing a close person to someone else in casual or polite situations.
Yes. "제 친구예요 (je chingu yeyo)" is polite and natural. You can also say "내 친구야 (nae chingu ya)" casually.
You can say "This is my friend" — 제 친구입니다 (je chingu imnida).
제 친구예요 means "This is my friend". It's the most common polite way to introduce a friend to someone else in Korea.
1. School/work: Bring friend to new group.
2. Social gatherings: At cafes, parties.
3. Helping join: Include friend in conversation.
This is my friend. My school friend.
This is my friend. A colleague. (Formal)
This is my friend, say hi! (Casual)
This is my close friend.