Learning a foreign language is both a pro and a con. I speak 4 – two fluently, and 2 very badly.
The pro is that you can converse with someone in another language, possibly making that person more comfortable. The con is that you may be talking to someone but excluding other people that are with you.
I speak a language that is totally useless outside of South Africa (Zulu). Completely useless. I also speak Afrikaans, which whilst useful in South Africa, does not really help in other countries except for the fact that it’s similar to Flemish, and derives from Dutch and French so I can understand a bit of Dutch and even some German. Wow, I guess that makes it quite useful!
I also learnt French. We did it in school, and then I did it University. I speak it very badly, and struggle to understand it. After so many years of French, you’d think I was far better, especially as I holidayed in France so many times. I talk French in France, on purpose. The French laugh at me, and try to correct me ( if they can be bothered, I think it’s so bad sometimes they can’t be bothered!).
The one thing I have enjoyed, is finding similar words, and the rudimentary understanding of where certain words come from and how they are derived. It’s fascinating. It’s also interesting how many words come from other languages, that once you start learning the other language/s, make themselves obvious.
That’s the real benefit of learning another language. The expansion of your knowledge regarding languages as a whole, as well as the learning about the country / culture of that language.
Some languages are amazingly descriptive, some are quite effective and efficient. Some are clear and easy, and some are very confusing.
Whatever the case, I think learning a foreign language can only benefit a person, expand their horizons, and best yet, let us make new friends in new places.