@babel/plugin-syntax-jsx enables Babel to parse JSX syntax. JSX is a syntax extension to JavaScript that allows you to write HTML-like structures within your JavaScript code. This plugin doesn't transform JSX into JavaScript; it only allows Babel to understand the syntax without throwing errors. It's a foundational dependency for any Babel configuration that needs to process files containing JSX, often used in React projects. Without it, Babel won't recognize JSX tags.