The Go standard library offers extensive functionality for image manipulation, exemplified by the image package, which allows developers to encode, decode, and manipulate various image formats effortlessly. Through the creation of a simple CLI application, users can convert PNG images into JPEG format while handling transparency by setting a background color. The lesson guides the implementation process, starting from reading a PNG file to encoding it as JPEG, and explores options to adjust the image quality and background color using the draw package. Key takeaways include the powerful capabilities within Go's library for image processing and project extensions like supporting JPEG to PNG conversion and adding CLI options for background color and image padding, showcasing Go’s versatility in building applications without relying on external dependencies.