First is LZB Nothalt, with this one I am not entirely sure, but I believe it serves as override of emergency braking forced by LZB safety system, for cases where it would make you stop on a dangerous place without access for emergency responders (tunnels, bridges). Second is a manual light aspect switch, the game forces you to use it frequently, but you should leave it to auto and control it from computer system instead. Usage can be for example when you have a cold loco at the end of consist and you want to show the red tail lights without having the whole system powered. Third is a switch for emergency light aspect, this varies between countries but usually is something like steady top white and flashing red left and right lamps. It signals "stop by all means possible" to oncoming trains and is used when for example some wagons in your train derailed and may be protruding to neighboring track where the other train is going to.
The opposite as far as I know. It's the switch to issue an LZB-emergency brake order across the system. You use PZB-Release to override LZB control. With the tunnels and so on, are you thinking of NBÜ by any chance? Just to add to this, they're not used in Germany to avoid any confusion.
I know about NBÜ, but I thought this could be a parallel system to it. Does NBÜ override PZB penalty brakes too? I always thought about it mostly as a system to get rid of passenger-induced emergency brakes. So it is rather an alternative to radiostop instead?
Not as far as I'm aware. I just read your comment about tunnels and thought of NBÜ since it's the only system I'm aware of that deals with tunnels and emergencies. I'm not familiar with this system and a quick Google search didn't help, but if it's a way to automatically stop trains via radio, then yes, it's similar. It doesn't stop a train immediately in all cases but defines a (moving) stop point for the trains following how LZB works.
PZB has it's own separate valve that is not affected by NBÜ (same with SIFA). The way I understand it on coach stock trains (not familiar with NBÜ on EMUs/light rail) when the passenger emergency brake lever is pulled this opens a valve in the affected coach so that the brake pipe is immediately vented. When the driver uses NBÜ (which typically only works with ep enabled since the switch is NBÜ/ep, iirc it uses the same pin) this sends a signal via the UIC cable to close all emergency brake valves on the coaches. EDIT: You typically don't lose all the air in the brake pipe though. The main reservoir is still charging the brake pipe on the locomotive (or cab car), which wouldn't be the case in SB, and the valve is probably smaller as well.
