constants-browserify exposes Node.js constants within a browser environment, enabling packages relying on these constants to function correctly in web browsers, specifically the constants related to operating system and file system operations such as os.constants. This ensures compatibility and eliminates "undefined" errors encountered when running Node.js modules that utilize these constants within a browser context, allowing for seamless cross-environment code execution. Browserify is a tool often used to bundle Node.js code for the browser.