The tag is present in Lintian version 2.109.6. That is the most recent version we know about.
This package declares in its symbols control file a dependency on some other package (and not one listed in the Provides of this package).
Packages should normally only list in their symbols control file the shared libraries included in that package, and therefore the dependencies listed there should normally be satisfied by either the package itself or one of its Provides.
In unusual circumstances where it's necessary to declare more complex dependencies in the symbols control file, please add a Lintian override for this warning.
Please refer to Debian Policy Manual section 8.6 for details.