app/code/Macademy/JsFun/registration.php

<?php
// New modules always extend from Magento Framework's ComponentRegistrar
use Magento\Framework\Component\ComponentRegistrar;

// All modules & themes are considered "Components"
ComponentRegistrar::register(
    ComponentRegistrar::MODULE, // This is a module...
    'Macademy_JsFun', // The name of the component is VendorName_ModuleName
    __DIR__ // __DIR__ specifies it is located in the current directory
);

app/code/Macademy/JsFun/etc/module.xml

<?xml version="1.0"?>
<!-- The module XML registers the module with Magento -->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <!-- Again, we define the name in the VendorName_ModuleName format -->
    <module name="Macademy_JsFun"/>
</config>