Japan And South Korea
Japan And Korea
With the 日 of 日本, the 日 means Japan. Then, you add Korea into the mix and you have Japan + Korea. This word means Japan and South Korea or Japan and Korea.
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.
This custom is frequently seen in both Japan and Korea.