Basically the person is trying to say that changes to the database structure causes you to change your mapping, and your
Java classes in something like Hibernate, whereas in iBatis has no mapping of database tables to Java objects, just mapping queries, and therefore a change in the database structure doesn't mean you have to change your mappings.
Now, my take, is that that isn't really an advantage. Because, in most cases database structure changes will mean to me that I still have to go into the mapping and change the queries, and I will most likely still have domain objects that probably will change too.
To me, the biggest advantage iBatis has over Hibernate is that it has a much smaller learning curve and has better stored procedure support.
Mark