monads : stuff which kind of encapsulate other things, but you can still nicely manipulate both the thing and the stuff. Let's say, lists.

monoids : set of things where you kind of can add one to another. Let's say, numbers

isomorphisms : functions where there is exactly as many outputs possible than there are possible inputs. Let's say, adding 1 to a number. It's kind of useful knowing whether or not a function is an isomorphism (hello, hash collisions !).

Those concepts aren't specific to any programming language in fact, and are in fact everywhere. You just don't need to explicit them to use them, expliciting them is an option (even in Scala) which allows you to do meta manipulations on them (which Scala doesn't require, and doesn't even really suggest since none are part of the standard lib).