what's new if swift?

Data Race Safety: Swift 6 introduces a new language mode that provides data race safety guarantees, helping developers write correct concurrent programs. This is a significant step in expanding Swift's safety guarantees to concurrent programming.
Non-Copyable Types: Swift 6 introduces non-copyable types, which are not copyable by default, enhancing memory management and performance.
Embedded Swift: A new language subset called Embedded Swift is introduced, which can run on highly constrained systems, making Swift more versatile.

Concurrency Model: Continued improvements to the concurrency model, including better data race checking and complete concurrency checking.
C++ Interoperability: Enhanced interoperability with C++, making it easier to integrate Swift with existing C++ codebases.
Typed Throws: Introduction of typed throws, which allows functions to specify the types of errors they can throw, improving error handling.
Low-Level Synchronization Primitives: New primitives for low-level synchronization, providing more control over concurrent programming.

Swift Package Manager: Ongoing improvements to the Swift Package Manager, making it easier to manage dependencies and build Swift projects.
Swift Testing: New testing APIs designed for Swift, making it easier to write and maintain tests.
Swift Assist: A new tool called Swift Assist will be available later this year, enhancing the developer experience with predictive completion and other features.

GitHub Migration: The Swift project will be moving to a new organization on GitHub (swiftlang), which will include the Swift Compiler foundation and many more Swift ecosystem packages.
Cross-Platform Development: Continued efforts to make Swift available on more platforms, including Windows and Linux, and improving cross-platform development tools.

For more detailed information, you can watch the session What’s new in Swift starting at 17:03.