So, imagine that you didn't believe that the earth was warming, or that humans contributed to that, or that we can't do anything to change that if it was the case, etc. etc.
Clearly anyone bringing attention to these so-called facts or proposing or implementing alleged solutions to the non-existing problem isn't actually achieving anything. They're just signalling virtue to others in their confused tribe.
Same with racism, sexism and any other fictitious problems that don't exist and that therefore don't have solutions. You can't fix problems that don't exist hence pretending the problem or a solution to it exists is just "virtue signalling".