Nobody mentioned reading the manual. I strongly suggest reading the manual for the Bronica ETRS before diving in head first. If you don't have it you can get a copy from
https://www.butkus.org/chinon/bronica.htm
Loading the film is not really difficult if you follow the instructions, but it isn't as simple as loading a 35mm film. The camera needs a 6v battery to operate (PX28 or 4LR44 or equivalent), this battery is in current production and easily available but you may need to buy it online. There are various interlocks that will confuse you if you don't remember them, eg the shutter doesn't fire unless the darkslide is removed. There is a shutter in each of the lenses. The body and lenses need to be cocked to (a) see through the finder, and (b) dismount or mount lens from body.
The shutter doesn't test-fire without film in the camera unless either (1) you take off the film back, or (2) operate the multi-exposure switch (don't forget to put it back). You can wind a roll of backing paper without film through to test the winding and shutter, but you don't have an extra roll of backing paper yet.