Is it safe to eat alone in Seoul?

Yes. Solo dining is extremely common in Korea. Many restaurants have 'one-person' sets, and you will not be looked at strangely for eating alone.

Do I need to know Korean?

Not really. Most younger people in Seoul speak basic English, and major tourist areas have signs in English. Learn 'Excuse me' (Jeogiyo) and 'Thank you' (Gamsahamnida).

Carry about 50,000 KRW in cash for small markets or street food stalls, but almost everywhere else takes international credit cards.

Navigating Seoul Solo for the First Time

Get a T-money card immediately at any convenience store to pay for subways and buses, and download Naver Map because Google Maps does not provide walking or transit directions in Korea. Seoul is incredibly safe for solo travelers; focus your transit on the subway system, which is numbered, color-coded, and operates in English.

Buy a T-money card. Go to a 7-Eleven, CU, or GS25 as soon as you arrive. Buy a physical T-money card for 4,000 KRW and load it with 20,000 KRW. Use this for every train, bus, and taxi ride.
Download the right apps. Delete Google Maps for directions. Download Naver Map or KakaoMap for navigation. Download Subway Korea to track train arrival times and transfers.
Master the Subway. Lines are numbered (e.g., Line 2, the green line). Follow the floor decals for boarding and look for English signage on platform screens. The subway runs from 5:30 AM to midnight.
Use KakaoT for Taxis. If you need a taxi, don't hail one on the street. Use the KakaoT app to book a regular taxi. It links to your credit card, so you don't have to worry about cash or language barriers.

Is it safe to eat alone in Seoul?: Yes. Solo dining is extremely common in Korea. Many restaurants have 'one-person' sets, and you will not be looked at strangely for eating alone.
Do I need to know Korean?: Not really. Most younger people in Seoul speak basic English, and major tourist areas have signs in English. Learn 'Excuse me' (Jeogiyo) and 'Thank you' (Gamsahamnida).
Should I carry cash?: Carry about 50,000 KRW in cash for small markets or street food stalls, but almost everywhere else takes international credit cards.