also: かくこくご
noun
each language; every language; various languages
Refers to multiple individual languages, often in contexts like multilingual support or comparison.
このサイトは各国語に対応しています。
This site supports various languages.
各国語の挨拶を調べてみた。
I looked up greetings in different languages.
外国語 means 'foreign language(s)' in general, while 各国語 emphasizes each individual language separately.
Compound of 各 (each) + 国 (country) + 語 (language). The reading かっこくご is a common euphonic change from かくこくご.