I don't care if you live in the most land-locked, single-language culture ever evolved by war, politics, economy and commodity, you should learn at least one foreign language.
It helps you with your own language.
It can make you more sympathetic to your fellow human beings.
It opens up experiences and encounters that you may not have had otherwise.
Let me explain further.
I had a decent education but the truth is that schools now spend far less time hammering the building blocks of grammar and language into the impressionable young minds of their students than they did previously*.
When you learn another language you become VERY aware what the different components of language are called, especially verbs, putting names and explanations to things you've only known instinctively before.
You have a better appreciation of how these components work together, especially when you're comparing how they work in your native tongue to how they work in your newly embraced language.
If you're a bit of a word nerd it affects how you see language in general and improves your use of it no matter which language you're speaking.
If you have the opportunity to travel to a country where your new language is spoken exclusively, take it.
You will never understand the immigrant experience better than you will the day you immerse yourself in a community where you can hopefully make yourself understood but cannot understand effortlessly.
It is impossible to overestimate just how alienated and claustrophobic you can feel when you can't understand the chatter of people on the train or when shopkeepers look at you patiently (or impatiently), waiting for you to make sense or to answer simple questions.
If you hear someone speaking in your first language you are overwhelmed with homesickness and you will approach strangers in a way you might never do at home just for the joy of unhindered, eloquent speech, no matter how banal the conversation topics.
But you pick up new words and tenses much more quickly and the simple pleasure of managing an everyday exchange is intoxicating, even if you know you sound like the instructions in a manual that has been translated from one language into another via a third, just making enough sense to get an answer or give one fills you with a sense of accomplishment.
Speaking a second language can allow you to meet people you might never have met, go places you might never have gone, form connections with people who you might not have bonded with without a key event or shared incident, offer help to people who feel as lost as you now know it is possible to feel, ask for help from people who (well-intentioned as they might be would have been unable to understand the tearful pleas).
It will make you re-evaluate the way you see other people and yourself.
It will make you a better person if you take full advantage of it.
Y'know, unless you just use it to pick up people of your preferred gender(s) and swear at people without them knowing it.
It can be used for that too, I guess.
*Also don't ask me about geography, I don't know anything about it worth a damn.