Hiroshima
proper noun
The wide island... this isn't helpful on its own, but this wide island is Hiroshima (heard of it?). When you do the reading it will make more sense.
The reading is the kun'yomi readings of both of these which is what you learned with the individual kanji. Just make sure you know those readings and you'll be able to read this.
広島はカキで有名です。
Hiroshima is famous for oysters.
広島空港から市バスで市内に向かってるところです。
I'm heading into the city from Hiroshima airport by city bus.
広島と長崎に投下された原爆は、一瞬で十万人以上の人々の命を奪った。
The atomic bombs dropped on Hiroshima and Nagasaki instantly killed more than 100,000 people.