Cyber attacks can target various parts of your IT systems. In some situations, an attack might disable important services that you provide, or they might overload your system entirely.
In other situations, the attacker's goal is to gain access to your system in order to impersonate someone at your business and steal or encrypt your data. The variant of such an attack called a “phishing attack” rely on sending emails to your staff that might appear to be from a trusted source only to contain malware that will infect your system.