I've owned several of those cameras. Mine were the more upscale Focusing Brillants, but they all shared essentially the same bodies. Most people in the Western world turn them into the extra "i" Brilliants. It refers to the view in the finder, which is, well, brilliant. Neat little cameras, w/ good to excellent lenses. If yours is like many of them, the markings inside the front of the lens is long gone, but even the lowest line lenses made great photos. If yours has a bakelite body it probably dates from 1937 upwards. I just used soap and water w/ a toothbrush to clean mine.
Now that you're hooked, you'll want to start lurking on the auction sites for one w/ a Heliar lens. Accept no substitute! I used to call mine a Hasselblad eater, because it was. If you need a mirror for yours, and I'm sure you do, there's a guy on eBay that sells them hand cut for a pittance. They work perfectly, because I sent him the exact measurements from mine back when he got into the TLR mirror making game. He makes them for Rolleicords and stuff too.