I think that’s a bug on the website: {}/1
The link shows the {} predicate from rdf11 (together with rdf_where), but the menu tree on the left hand side shows the clpqr module, which also includes a {} predicate. Seems like the lookup for the left hand part is not module sensitive.
How did I get there? Easy - just lookup the documentation for the semweb/rdf11 package and click on {} on the left hand side.
My apologies if this is already known - it’s only a tiny inconvenience anyway.