What does ''NAV ILS OUT OF SERVICE'' mean?
It means exactly what it says. The ILS is out of service, so you can't use it.

An ILS can consist of several different elements, for example localizer, glidepath, DME, inner/middle/outer markers as well as a bunch of technical monitoring equipment, ATC control panels, warning systems and backup power supplies. Should any of these components fail, it may be required to take the entire system out of service. The NOTAM doesn't say exactly which part of the ILS is broken, but that doesn't matter, since the entire ILS is listed as unavailable. So no, you cannot expect to use the localizer.