Cybersecurity is the practice of protecting systems, networks, applications, and data from unauthorized access, disruption, or destruction. Strip away the buzzwords and it's about three things: keeping information confidential, keeping it accurate, and keeping it available when it's needed.
That trio — confidentiality, integrity, availability — is the foundation security people refer to as the CIA triad. Every control, framework, and tool in the field maps back to one or more of those three properties.