Noun and の adjective
がいこく
わたしたちはまだ外国に行ったことがありません。
We haven’t gone to other countries yet.
外国へでんわをするのはこれがはじめてです。
This is my first time making an overseas call.
もし外国にいるなら、有名人になっても構わない。
I wouldn’t mind being a celebrity if I was in a foreign country.
An outside country is one outside of your own country. That is a foreign country.
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.