This is the 5456th most frequent Russian word.
платежных
"Платежных" means "of payments" or "payment-related" in English.
Here, 'платежных' modifies 'операций' to specify that these are related to monetary payments or transactions.
В этом банке можно открыть счет для платежных операций.
In this bank, one can open an account for payment transactions.
In this sentence, 'платежных' describes 'данных,' referring to data associated with monetary payments.
Компания ввела новую систему для обработки платежных данных.
The company introduced a new system for processing payment data.
Here, 'платежных' applies to 'систем' to denote systems that handle monetary transactions.