There's no better way to learn about a culture and its people than to learn their language. Their fay-to-day colloquial language - not that formal from a textbook stuff. Of course we here in the U.S.A. g=have turned that into a political football thanks to the immigration issue. When I was in school learning Spanish was considered a good thing - now many folks consider it a travesty to learn the language of our large neighbor to the south. Me? I know enough Spanish for the important stuff - Mas cerveza por favor. Mas tacos por favor. You see where I'm going, I'm sure.
My friends and I took German in high school and I took an additional 2 years in college. At one point I was quite fluent and thanks to a couple of German brothers at the McDonalds where I worked at the time I could cuss you out fluently as well as tell you to perform a physically impossible act upon your self - good old Merle.
The latter doesn't seem to translate quite as well as the former - Komm gibt mir deine hand - Come give to me your hand isn't quite the same as I want to hold your hand - LOL - but these were both classy shout outs to the land where the Beatles spent their early career playing dive bars and the like.
Some songs need no translation to get thir meaning across -
Then there's my all-time favorite foreign language song - one that had everyone I know humming and singing along even though for all we knew it could have been about bean sprouts and fish eggs. It just sounded - and still does sound - wonderful. In fact it is one of my all time favorite tunes - I'ma big melody guy.
I am also in the camp that the same language can be made new in different environments. Who can deny the difference in English between Canada, the US and UK. In fact American English has many varieties - as do the other 2. Cuban Spanish is quite different sounding friom Mexican Spanish. I suppose one's definition of a second language may need a bit of specificity attached to it.
Whatever your definition, I think learning a second language is a good thing and whenever possible something we should take advantage of.