auto.home is an NIS map, where the source resides on the NIS master server. It doesn't exist on the local machine.
There is a chain of maps being used from an auto.master map (also in NIS) which references the NIS auto.home map.
What helps this section is to actually carry out the previous section yourself, and play with it. That section uses local files only. Once you get the idea of how that is functioning, what this section does is show how NIS maps may be used to substitute for the local /etc automount files. This works as long as the /etc/nsswitch.conf file entry for automount contains NIS.
You can even make the line "automount: nis" only, and it will only use the NIS maps.
The purpose here is to demonstrate using a centralized database to determine where a particular users files are stored. That makes it easier to manage a network of hosts and eliminates the need to directly admin each system separately, and allows for a centralized backup service for the users files. Once that is done, it becomes easier to drop making system backups (you only need to save the custom configurations), and simplify general administration. (hint, one thing not yet mentioned is having a remote log server so that each system sends its logs to that server instead of storing them in /var/log.)
Now NIS is being depreciated (it hasn't got the best security features), but the next example uses LDAP for the same purpose. LDAP is a bit more complex, so using NIS for the examples makes it simpler to understand.