The folks at
Open Culture published a
listing from the Foreign Service Institute of which languages are the hardest for native English speakers to master. The FSI is the language-training service for the US government, and the article also includes a map of Europe color-coded to show some of the languages for that part of the world.
The European map is interesting because of the little gray patches on the edges of England and Ireland. One seems to be in Scotland, one in Ireland and one in Wales -- although the map legend says those areas are unclassified, we can presume that they are where the languages of Scots Gaelic, Irish Gaelic and Welsh still have a fairly strong hold. We can presume that these languages are difficult to learn because it's pretty tough to know what Scots people are saying when they're speaking English, the Irish are deep into a pint of stout and Welsh doesn't even have any frickin' vowels in half the words.
In the list we see languages divided according to difficulty, along with the hours of study needed to learn them. The first group has languages considered the most similar to English and they are usually mastered the quickest. It's interesting because although many of the languages are similar to English they are not all that similar to each other -- your average Afrikaans speaker can't just stroll down a Lisbon
rua and begin chatting up the ladies without some serious language software on his
selfoon.
The two hardest tiers are languages that come from mostly non-European cultures which also frequently use different writing systems than English. German doesn't reach that level, for example, because although the German alphabet has some additional characters in it like ẞ, it still has a lot in common with English. But the other languages listed vary widely from the English language and the strongly European-derived brand of culture of the US.
Not listed on the chart is the arrangement of jargon your average woke college student or politician at a press conference speaks on a regular basis -- although most of the words involved
are recognizable as English, they have been strung together in an arrangement that makes no damn sense.