This is the 487th most frequent Japanese word.
拡大
Expansion.
In this sentence, "拡大" refers to expanding or increasing scope or scale, specifically in a business context.
その会社は事業を拡大しています。
That company is expanding its business.
Here, "拡大" is used to describe enlarging or zooming in on something visual, like a map, to see it in more detail.
地図を拡大して、細かい場所を確認しました。
I zoomed in on the map to check detailed locations.
In this example, "拡大" indicates the spreading or proliferation of something, in this context referring to the spreading of diseases.