전보가

a telegram

→ 전보
phrase Rare #21,508
a telegram 전보 means “telegram,” and 가 is the subject particle. 전보가 오다 literally means “a telegram comes” and naturally means “a telegram arrives” or “to receive a telegram.” This expression is old-fashioned because telegrams are rarely used today.
KO: 방금 전보가 왔어요.
EN: A telegram just arrived.

전보가 왔어

A telegram has arrived.

— 이웃집 토토로 (1988)

전보가 왔어요

A telegram has arrived.

— 이웃집 토토로 (1988)

여보 전보가 왔어요

Honey, a telegram has arrived.

— 아메리카의 밤 (1973)

긴급 전보가 왔는데

An urgent telegram came in, but…

— 인생은 아름다워 (1997)