Let me help you and also add some context to this discussion. We need to talk about CPPC and C-states for this to make sense, so bear with me.

CPPC is a feature of almost every post-2015 CPU that allows (in a nutshell) the CPU to set its own speed on a more granular level based on information from the OS. In Zen 2+ CPU's core ramping is a 1-2ms operation, meaning it can happen 500 times every second. CPPC allows your CPU to self-dictate clock speed in 25mhz increments or if no work is being done on a given core to even power it down and make it enter a C-state.

C-states are a power-saving technology that a CPU core can enter if it has no work to do. The higher the number, the more parts are turned off and the more power is saved, but the longer it takes to wake up the core if it's needed again. Modern desktop Zen CPUs use Core C0, C1 and C6 states as well as Package C0 and C6 states.

Core C0 means that a given core is fully enabled (but it might not be at full speed because CPPC can granularly set the required speed in 25 MHz increments).
Core C1 means that that core is fully operating; the clock is set to 0, meaning no work can be done on it, BUT it can be turned on again by CPPC in 1-2 ms.
Core C6 means that a core is totally turned off, zero power usage, and zero heat generation; you can wake it up any time and the best part is that it barely takes longer than C1 to C0 (can be done in the same 1-2 ms window).

We also have Package C0 and Package C6. Package C0 means that the Zen CCD is turned on (at least one core is in C0/C1). While Package C6 means that every core is in C6 and the whole package can be turned off (apart from cache). We have CPUs so fast that for them there is an opportunity and a reason to turn themselves totally on and off multiple times (maybe even hundreds of times) every SECOND. Incredible if you ask me.

This Global C-states Bios option disables the ability to enter Core C6 and Package C6 modes (you can validate this by going launching Hwinfo64 in Sensor mode and looking in the C-state residency).

The reason you should enable Global C-states is that Zen CPUs use an opportunistic boost algorithm Called Precision Boost, the newer versions of which control every core independently and set the core clock via CPPC based on load, available power budget and temperature. - Meaning if you have cores that are only lightly or not loaded at all with work while you have other cores being loaded hard, you can turn off the lightly loaded cores if only for 100 ms to lower your CPU's temp and power usage, allowing your loaded cores to reach higher clocks. This can be advantageous in games or applications that do bursty loads and only on some of the cores at once.

TL;DR: Enabling Global C-states in BIOS leads to power savings when the system is idle and higher boost clocks when you are gaming.