babel-plugin-transform-es2015-block-scoped-functions transforms ES2015 block-scoped functions into ES5-compatible code. This Babel plugin ensures that functions declared within blocks (e.g., if statements, for loops) are properly hoisted and scoped, preventing unexpected behavior in older JavaScript environments. It handles the complexities of ES6 function scoping, contributing to cross-browser compatibility when transpiling modern JavaScript. Using this plugin allows for safer and more predictable execution of block-scoped functions in legacy browsers.