First up: create a file inside of your _data folder called helpers.js and add the following to it:

module.exports = {
  currentYear() {
    const today = new Date();
    return today.getFullYear();
  }
};

Now, on your templates, you can do something like this:

<footer role="contentinfo">
  <p>Copyright {{ helpers.currentYear() }} My Awesome Site</p>
</footer>

This trick uses JavaScript Data Files which I love using to create global helper functions like the above. They’re extremely handy and one of my favourite Eleventy features.