Lets take J:F:C:20230425 as example
As far as I know:
The first letter refers to regions, which can be J (Japanese), A (Asia) and K (Korean)
It mainly affect the language that the game displays, J will be in all Japanese, A will be in mostly English and K will be in mostly Korean.
The second letter refers to models, which can be F (old model) and G (Valkyrie model)
As for the third letter, I have no idea.