What does Query matching all documents (typically mixed with a boolean query) mean?

Hibernate Search
1

I have below code specific to hibernate search 5
We wanted to understand qb.all() what is mean by Query matching all documents (typically mixed with a boolean query) ?

is it matching all the documents with all types of fields?? if yes, then if we need to exclude other type like boolean or dates then how we can exclude those ?

    final Query query;
.....
....
    query = qb.all().createQuery();
}