I'm a native English speaker from the US, and did terribly at foreign language classes in school.

Later in life, I spent 5 or so years learning Mandarin (speaking, reading and writing, traditional and simplified). I still speak it everyday and lived in Taiwan for years. Learned a bit of Taiwanese Hokkien, mostly for the food.

Recently moved to the Philippines for work and have to speak a little Tagalog, though most people in the business world here speak great English.

A new language in always in context, and you gain some new personality traits with it. My Chinese expression is more precise and logical than my English, partly because I lack the rhetorical skills to bullshit so I can't really afford to. My (very basic) Tagalog is entirely focused on making friends and diffusing tense situations, because rolling with the punches and making friends fast is an important life skill in the Philippines.

For non-human languages, I do data analysis by trade and have a very different approach to programming than traditional software engineers. I tend to use and write in the functional rather than the imperative style. Examples include Scala, R, and some uses of Python. When working with new developers, I usually spend some time introducing the paradigm and why it can help data driven products.