Project Service Automation (PSA) is an integrated suite of solutions designed to help project-based organizations manage services from sales to invoicing within Microsoft Dynamics 365. It offers benefits such as streamlined project estimation, resource management, and simplified billing, facilitating team collaboration and enhancing client satisfaction. PSA includes various modules that support opportunity management, project planning, time and expense tracking, and service analytics, making it a comprehensive tool for optimizing project delivery and profitability.