This is a command to start VNC server under Linux system, which is explained as follows.

1, systemctl is a system management command, which is used to control Systemd system and service manager.

2.start: means to start the specified service.

3.VNCServer @: 1.service is the service name of VNC server, where @: 1 means that the port number for starting VNC server is 1, and the port number can be modified as required.