Questions about DNS Custom Filter's

Running a Galaxy A8 (2018) using latest AG (as per screenshot) but have either overlooked an explanation or I just can't get it in basic.
Under the DNS Category, is a "new" feature called "DNS USER FILTER" which is self-explanatory. BUT trying to get it explained...
According to the KB page, it has to follow a certain syntax. I get all that. UNTIL the examples as per another screenshot. WHAT & HOW DO YOU USE: etc/hosts? The description is: “Hosts” rules, which is basically the same as etc/hosts
Does this new feature mean we can write or modify our own DNS filters? Or copy/paste like User Whitelist/Scripts? Where can we get a copy if there's any?
A HOST FILE is written a certain way with it's own syntax if I'm correct. The DNS SYSTEM follows a certain syntax & format as well. Yet they can be combined?!?