Neither one nor other. The function in Root is just a search. The @filter itself is a filter and filters can use any existing function in Dgraph.
Using connectives Get started with Dgraph
Connectives you could consider as multiple conditions.
What do you mean by column?
ah, I get it about column! But not sure what you want. Check the Connectives link above and lets see.
Also Check our tour A Tour of Dgraph
Cheers.