Amazon S3 Access Grants is a new feature that simplifies data access management for S3 data lakes. It allows granting S3 permissions directly to directory identities like Active Directory users and groups, enabling granular access control at scale. The video explains how Access Grants works, its key benefits including end-to-end auditing, and walks through a typical use case for analytics workloads. It also highlights how Access Grants integrates with AWS IAM Identity Center for seamless identity management across AWS services.

Key features of S3 Access Grants include the ability to define intuitive, grant-style permissions, just-in-time credential vending, and detailed CloudTrail logging of end-user access. This helps organizations better govern their S3 data, especially for data lake and analytics use cases involving data scientists and engineers. The speaker demonstrates how Access Grants can be used to control access to different datasets within a centralized data lake bucket, serving both technical and business users.