Switching and routing topic

Im not able to assign the Ip adress and lab is not getting clear for me in this topic kindly please suggest me on this , im not getting proper clarity on eth0 ,why we are specifically assigning that value.
please exlain in brief

eth0 is the name of the interface. That’s what you see in the output of the ip link command. So you must use that device name while assigning IP address.I see you are using an interface name eth01 which is why you are getting the error. Please use eth0 instead.