S. 4075, titled the "Protecting Privacy in Purchases Act," aims to prevent payment card networks and entities involved in processing transactions from assigning or requiring special merchant category codes for firearms retailers that differentiate them from general...
Simple Explanation
In this bill, it says that credit card companies can't use special codes to tell if you're buying something from a gun store instead of a regular toy or sports store. This means they won't be able to track or label gun store purchases differently from other types of stores.