Discernment is key to be able to recognize it. Like truth. Truth doesn't exist as a thing in itself. We have many words to describe reality, truth is one, good and evil are other among many :) They are very valuable descriptors :) We can describe them personally and collectively if we agree on foundational definitions and principles that are used to discern them.
We can describe them and live by them yet, it doesn't mean that they actually exist. Much like the concept of money.
Neither does love. It doesn't diminish the value of the words to describe things just because they aren't primary substances in themselves. Color doesn't exist in itself either, only specific color frequencies do, but color itself is not something that exists in itself. Some things are expressed and exist through primary substances that do exist in and of themselves. Actions exist, and those actions that harm can be characterized as evil, even if evil doesn't exist in and of itself separate from the primary things it is expressed from.