Years ago, it was common to have the "language" attribute within the script tags. This attribute was used to specify the scripting language of the contents of this element.
Since the "language" attribute is not standard, it is obsolete and should be removed. For JavaScript, the "type" attribute is optional too and can be left out.
<script src="script.js" language="javascript"></script>
❌ Figure: Bad example - The "language" attribute is obsolete
<script src="script.js"></script>
✅ Figure: Good example - No "language" attribute, and "type" omitted since JavaScript is the default
Read more on MDN - The Script element.