In addition to the fine information accn gave, I will add a few thoughts.
Like cpus memory comes with a base clock and a boost clock. The speed you see advertised on the ram is actually the ram maker saying you we validate that you can overclock to this point, say 3200 for instance.
The memory is likely though base clocked at 2133 or 2400 as these are the only 2 standards I know of for DDR4.
Anything over that is enabled by setting a manual overclock or utilizing the boards if supported validated OC profile for the ram either called XMP or DOCP depending on the board maker. This is however an overclock according to AMD and using it could void your warranty. That of course is ridiculous as the memory maker and AMD promote the usage. So if you have an issue and have to RMA just don't tell them you used XMP or PBO for the the auto CPU performance improvement.
3200 is pretty much the sweet spot in games and going higher will cost a lot more and not gain as much as the initial jump to 3200. Don't be worried about using XMP as in practice it is safe and I have never heard of anything failing because of its use.
Do realize that going faster in the speed can show flaws that are not there at slower speeds.
Your mother boards maker will have QVL lists that validate what memory has been tested with their boards and they know it works. These charts may include or have different charts depending on bios revision and which CPU generation is used. So choose accordingly.
