This lesson provides an overview of testing and fixing accessibility issues in your WordPress content to ensure it is usable by as many people as possible. It covers the importance of accessibility, built-in WordPress tools for checking semantic structure and color contrast, and recommends plugins like WP Tota11y, Sa11y, and Editoria11y for additional checks. The lesson also suggests using OS apps and browser extensions to test technical aspects and emphasizes that authors and content managers can significantly improve accessibility without coding by being mindful of key elements such as heading levels, text size, color contrast, links, and alternative text for images.