Authors details such as social media links, emails etc → Is this Meta or something else?

Add user contact methods using the user_contactmethods filter in your theme’s functions.php or via a plugin:

User contact method entries are stored in the wp_usermeta table. The URL field is special; it’s stored in the user_url field in the wp_users table.

// Add user contact methods
add_filter( 'user_contactmethods','wpse_user_contactmethods', 10, 1 );
function wpse_user_contactmethods( $contact_methods ) {
    $contact_methods['facebook'] = __( 'Facebook URL', 'text_domain'    );
    $contact_methods['twitter']  = __( 'Twitter URL', 'text_domain' );
    $contact_methods['linkedin'] = __( 'LinkedIn URL', 'text_domain'    );
    $contact_methods['youtube']  = __( 'YouTube URL', 'text_domain' );

    return $contact_methods;
}

Output the links in your template file:

<div class="author-box">
    <div class="author-image">
        <img src="http://blog.blogeto.com/html/images/author_profile.png" alt="">
    </div>

    <div class="author-description">
        <h2>
        <!-- AUTHORS NAME --> <?php the_author(); ?>
        <!-- <a href="<?php echo get_author_posts_url( get_the_author_meta( 'ID' ) ); ?>"><?php the_author() ?></a> -->
            <?php 
                // Get the id of the post's author.
                $author_id = get_the_author_meta( 'ID' );

                // Get WP_User object for the author.
                $author_userdata = get_userdata( $author_id );

                // Get the author's website. It's stored in the wp_users table in the user_url field.
                $author_website = $author_userdata->data->user_url;

                // Get the rest of the author links. These are stored in the 
                // wp_usermeta table by the key assigned in wpse_user_contactmethods()
                $author_facebook = get_the_author_meta( 'facebook', $author_id );
                $author_twitter  = get_the_author_meta( 'twitter', $author_id  );
                $author_linkedin = get_the_author_meta( 'linkedin', $author_id );
                $author_youtube  = get_the_author_meta( 'youtube', $author_id  );

                // Output the user's social links if they have values.
                if ( $author_website ) {
                        printf( '<a href="%s"><i class="fa fa-home" aria-hidden="true"></i></a>',
                                esc_url( $author_website )
                        );
                }

                if ( $author_facebook ) {
                        printf( '<a href="%s"><i class="fa fa-facebook" aria-hidden="true"></i></a>',
                                esc_url( $author_facebook )
                        );
                }

                if ( $author_twitter ) {
                        printf( '<a href="%s"><i class="fa fa-twitter" aria-hidden="true"></i></a>',
                                esc_url( $author_twitter )
                        );
                }

                if ( $author_linkedin ) {
                        printf( '<a href="%s"><i class="fa fa-linkedin" aria-hidden="true"></i></a>',
                                esc_url( $author_linkedin )
                        );
                }

                if ( $author_youtube ) {
                        printf( '<a href="%s"><i class="fa fa-youtube" aria-hidden="true"></i></a>',
                                esc_url( $author_youtube )
                        );
                }
            ?>
        </h2>
        <p> Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s.Lorem Ipsum is simply dummy text.   <a href="#">Read More</a> </p>
    </div>
    <div class="author-category">
        <ul>
                <li><a href="">CATEGORY 1</a></li>
                <li><a href="">CATEGORY 2</a></li>
                <li><a href="">CATEGORY 3</a></li>
                <li><a href="">CATEGORY 4</a></li>
                <li><a href="">CATEGORY 5</a></li>
        </ul>
    </div>
</div>