This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
I was so busy I forgot to buy a train station bento.
One fun thing to do during domestic trips in Japan is to compare various station bento.
Oh, you forgot to bring the onigiri? We’ll have to buy a station bento for lunch.