This phrase is not exactly a slang, but a popular saying in Spanish, which means 'He who doesn't learn, it's because he doesn't want to'. It's used to express that when someone doesn't learn or understand something, it's not due to a lack of resources or opportunities, but due to their own lack of interest or effort.
Examples
- Spanish: Le he explicado las matemáticas varias veces, pero sigue sin entender. Como dice el dicho, 'el que no aprende es porque no quiere'.
- English: I've explained the math to him several times, but he still doesn't understand. As the saying goes, 'he who doesn't learn, it's because he doesn't want to'.