Get ready for some memorization! The first number represents the “Portfolio Year”, which for 2023 will be 7. This makes sense as Ryzen 7000 is next up, and in 2024 we will presumably have Ryzen 8000 parts (Portfolio Year 8). The next one seems more arbitrary, as it refers to “Market Segment”, which would in theory be a “5” for Ryzen 5, but in this case is a “6” for a Ryzen 5. But “9” is the highest, which does make sense.
The third digit is the easiest to digest – and the most important: Architecture. Simply put, “4” means Zen 4. (Be on the lookout for products with a “2” here.) There are a couple of additional boxes to learn, with “Feature Isolation” representing a “plus” (i.e. Zen 3+) with a “5”, and a non-plus with a “0”, for … reasons. And then of course you have the Intel-esque Form Factor/TDP letter at the end, which in this case is a “U”.