In case you are in the UK and are considering a new language to learn..
The British Council has a fairly recent (2017) report on what they believe to be the most important foreign language skills for the UK workforce, given the current business, diplomatic and cultural needs. This wouldn't automatically apply to other English-speaking countries.
Their conclusions?
Top 5 languages to learn: Spanish, Mandarin, French, Arabic, German.
The next 5: Italian, Dutch, Portuguese, Japanese and Russian.
The full report is here: https://www.britishcouncil.org/research ... uture-2017
The report has many interesting facts on language skills in the UK, and the case is made of each of the 10 languages above. You might for example be surprised by the inclusion of Dutch, which is a relatively small language, but it is listed due to the importance of UK-Dutch trade and business.
[Note: Reposted from Duolingo forum Nov 2020]