Languages don't divide the world in the same way
We sometimes imagine that languages are just different labels for the same things.
But they are actually not.
One language may have a single word for something another language needs a whole sentence to explain. Another may make a distinction that simply isn't important in your own language.
And that's where things get interesting.
Learning another language can make you notice ideas, relationships, and even small details that you had never really needed to think about before.
You're not always just learning new words, sometimes you're learning new places to look for.