I am a network administrator and here is what it mean:
The terms network administrator, network specialist and network analyst designate job positions of engineers involved in computer networks, the people who carry out network administration.
Network administrators are basically the network equivalent of system administrators: they maintain the hardware and software that comprises the network.
This normally includes the deployment, configuration, maintenance and monitoring of active network gear: switches, routers, firewalls, etc. Network administration commonly includes activities such as network address assignment, assignment of routing protocols and routing table configuration as well as configuration of authentication and authorization – directory services.
It often includes maintenance of network facilities in individual machines, such as drivers and settings of personal computers as well as printers and such. It sometimes also includes maintenance of certain network servers: file servers, VPN gateways, intrusion detection systems, etc.