Access in a cyber security context refers to the 1) physical access someone may have to a system and 2) online or network access a person or system may have to a machine, device or other system.
In an online context, and at the time of writing, access to a system or device may be through a username and password, through a biometric device such as a fingerprint scanner, through a pin code or code provided by a fob or sms for example. Access to a system could also provided using a combination of these methods. This is known as multi factor authentication. In the case of 2 factors or types of authentication being used it is termed 2-factor authentication.