One of my best friends in elementary school was a son of Turkish immigrants.
His parents didn't speak any German, so naturally he had serious issues with the language, too.
This held him back in school, which lead to him getting sent to the lowest tier of secondary school.
(We have 3 tiers in Germany. The highest one (Gymnasium) qualifies you for university, the middle one (Realschule) used to qualify you for highly-skilled work that doesn't require university, and the lowest one (Hauptschule) for the trades. Nowadays, even trades jobs scoff at the middle tier, and the lowest tier is basically a direct route to a life of shit jobs or unemployment.)
But just by hanging out with him as a friend, I taught him German, how to use and fix computers, showed him the world of books, and connected him to German society better. I'm not trying to brag, he was a very bright kid and it wasn't like I was doing this as welfare, he was just a good friend and we shared what we liked with each other.

25 years later we met again by accident. He actually recognized me when he saw me on the street in a different city.
By then he had switched from Hauptschule to Realschule, went on to get his qualification for university, studied economics, created his own company in the IT sector, and had 6 employees. And he told me that my friendship was what kept him out of the wrong circles. On the old computer I had given him (which my parents had replaced) he had taught himself how to use office programs, so he was the only one in the family who could do the taxes, which taught him about finances.
At the time I met him again I was actually unemployed and working odd manual labor jobs under the table, after failing my university education twice due to depression.
He connected me to some contacts he had, which landed me an IT support job, and now I have a pretty good career as a sysadmin.