It's one of the large family of plate cameras in this size. The holders may have sheaths in them to hold film; if not, the sheaths can be found or made. From the picture, it looks like the camera is in good shape and might make a fine shooter.
As far as I know, the only 9x12 films in regular production are Efke 100 and Fomapan 100; Efke 100 is available from Freestyle. I suppose you could cut down 4x5, but precision cutting in total darkness sounds like a pain in the neck. Plates are essentially no longer made; they sometimes turn up on eBay, but their usability is a crapshoot. That said, it's kind of fun to shoot them and find out what happens. Rollfilm backs for shooting 120 (usually 6x9) in these cameras also exist but are kind of expensive.
Once you have the film, it functions like a fairly normal large-format camera: compose and focus on the ground glass, CLOSE THE SHUTTER, take the ground glass out and put the film holder in, STOP DOWN THE LENS, pull the darkslide, shoot, REINSERT THE DARKSLIDE, remove the holder. (The steps in caps are the ones you will inevitably forget some of the time.)
Freital seems to be the city in which Erko was based; from what I'm seeing in Google, the lens seems most likely to be a Selar, which apparently is a four-element symmetrical anastigmat like the Voigtlaender Eurynar (see
http://forum.mflenses.com/unknown-beier-9x12-german-plate-camera-t32450.html, which has some analysis of a similar camera with this lens). It's not clear to me if Erkos made the camera or just the lens.
I really like these prewar plate cameras---they're very compact and a simple point of entry to the highly addictive large-format world. Enjoy it!
-NT