Basing on how much it is important to understand categories to know mathematics or to know other languages, I would say nothing. But probably it can be fun, and

Basing on how much it is important to understand categories to know mathematics or to know other languages, I would say nothing. But probably it can be fun, and definitely you can then brag about it. However, if you still have to learn X, don't try to learn categories to learn X. First learn X decently, then if you want learn categories (or any algebraic abstractions that people say it is useful) and you have some hope that categories will give you some additional insights on X.