A "third party payment service provider" is a non-bank that provides payment initiation & account information services.
A third-party service provider can be a FinTech company, for example. They require consent to access your bank account and must first establish themselves as a payment initiation service provider or account information service provider and obtain the appropriate regulatory approval or register with them.
While the former can help you process a payment, the latter can give you a better overview of your finances.