What is Wordpress Malware Infection? How do you deal with it?

In WordPress websites, we generally install third-party plugins/themes for integrating additional features. But most of the time, we are not aware of the inherent security vulnerabilities of these plugins/themes which act as critical loopholes that are targeted by hackers/malware botnets, etc. Some plugins provide regular updates for patching those issues. But if we fail to do them, it leads to the exploitation of the vulnerabilities and severe malware infection.