FED cameras are well-known made-in-USSR Leica derivatives. There are five common models (FED-1 to 5) and each model has a plethora of variations. The camera that I present here is an early FED-3.
There are two main variations known of the FED-3, viz. the first version with advance knob (FED-3a) and a second version with advance lever (FED-3b). This camera is of the earlier type. Another subcategorization is made based on the engraving in front: single language cyrrilic script (ФЭД-3) or dual language engraving (ФЭД/FED-3). The early versions, like this camera, only have single language cyrrilic script.
You can read more details regarding the differences between all the version on the website of SovietCams. According to their categorization system, this camera is one of the ~40.000 PE0615 cameras released by Kharkov (cf. serial number 2057983).