I have quite a good perspective on this one I think. I was naturally good at languages at school and ended up doing a degree that combined French and Spanish with law. I am “domestic fluent” in French having been an au pair and in both languages I can speak, read and listen at business level, but would not be able to draft a business communication to the requisite standard. Once I had Spanish under my belt I took Portuguese classes as it is a fairly straightforward add-on to Spanish and French. I then spent some time working in Brazil (I was sent there by my firm because I had reasonable Portuguese, though the actual work was all in English) and I have continued to work regularly with Brazilians throughout my career.
Later I spent a decade working in Asia. I lived in Hong Kong and travelled regularly to mainland China. I was surprised to find it almost impossible to pick up conversational Cantonese just by going about daily life as, with it being a tonal language and an unfamiliar script, it was impossible for me to distinguish individual words, and any attempts to speak were so incomprehensible to the locals that it was much easier for them to speak English to me, or use a translation app. Mandarin is marginally easier than Cantonese to learn (fewer tones) and I did make some progress after a few lessons but it was painfully slow compared to my experience of Romance languages (I was doing it more for fun/curiosity though, so no real pressure to learn). I am back in the UK now and there are three kids in my son’s class with Chinese Mums, but I could not come close to chatting to them in Mandarin. I noticed on a few trips to Japan that Japanese felt more accessible as it is not tonal in the same way.
I work with a lot of Indians now as I have some involvement in software development. They all work in English, and I know that they do not all share Hindi as a language anyway (Hindi, Malayalam, Tamil, Gujurati, Bengali, all very different languages).
In my view, language skills in international business, office type work are not that useful. For every British person who is an adult learner of Mandarin/Arabic/Spanish there will be 10 people who grew up bilingual in English and one of those languages and who have additional professional skills to offer. They have the benefit of not just linguistic understanding but innate cultural understanding and they are much more likely to understand the psychology, and gain the trust, of native speakers than a British learner. Plus AI translation tools are now extremely sophisticated; we are basically at the Babelfish stage now (Douglas Adams reference there!)
The other thing is that even though I speak business French, Spanish and Portuguese, I rarely use it because it is rarely just me and the speakers of one of those languages in the room/on the call/on the email chain- there will be someone else who speaks English only, or who speaks German or something plus English, and all the work is done in English anyway. At most, it helps when they can forward me an email chain with some Portuguese in it, or point me to a website in French only without having to summarise what it says as I can read it myself (though Google translate also works for that, pretty well). It does also give me novelty value and help me form good relationships if I can do a bit of chit chat in their language at the start of a meeting but that would be rude as soon as a monolingual English speaker joined the call.
Langauges are useful for work if you need to go and live in a foreign country to work, so that you can live your daily life comfortably, outside the office. At work itself, not so much unless you are bilingual.
The type of work where I think languages could be very helpful might be in the UK doing something like working with refugees or disadvantaged people from immigrant communities, people who cannot speak English but need support navigating the UK benefits or legal system, finding jobs, getting medical treatment etc. eg I could imagine that if I were a doctor it would be great to be able to take a medical history and explain a diagnosis to a Brazilian migrant worker without needing an interpreter. People whose limited English might fail them when they are scared or upset. But you don’t have those interactions in international business. And for that reason I agree that a bit of Mandarin or Hindi(or Polish or Ukrainian) might come in handy for say a social worker, but you’d need more than a smattering to make it helpful. And, again, there will be natives if those communities working in public service.
Therefore I’d counsel you against learning anything on the basis that you think it will have a real benefit for work unless you have a clear future opportunity already in your sights. But if you do want to learn something I would suggest Portuguese, specifically Brazilian Portuguese, which is much easier to understand than that spoken in Portugal. It sounds beautiful, opens up so much fabulous music, it’s a huge growing economy and has a massive diaspora.I hear Brazilians on pretty much every tube journey I take in London. It’s also a fascinating place to visit and if you go there, English is not all that widely spoken outside the business/tourist world so it is very helpful, and you can make a HUGE positive impression when they realise you speak it, as so few people ever do.
Sorte!