Koreans use it when giving directions on the street, in a taxi, or while guiding someone to a place.
Yes. "왼쪽으로 도세요 (oenjjogeuro doseyo)" is polite and natural. You can also say "왼쪽으로 돌아 (oenjjogeuro dora)" casually.
You can say "Turn left" — 왼쪽으로 도십시오 (oenjjogeuro dosipsio).
왼쪽으로 도세요 means "Turn left". It's a polite direction instruction.
1. On street: Giving walking directions.
2. In taxi: Telling driver which way.
3. Guiding friend: Helping someone find place.
Turn left. It's over there.
Turn left at the next corner.
Turn left here. (Casual)