Rename "Posts" to "Articles" in the Admin

add_filter( 'post_type_labels_post', function ( $labels ) {
    $singular = 'Article';
    $plural   = 'Articles';

    $map = array(
        'name'                  => $plural,
        'singular_name'         => $singular,
        'add_new_item'          => 'Add New ' . $singular,
        'edit_item'             => 'Edit ' . $singular,
        'new_item'              => 'New ' . $singular,
        'view_item'             => 'View ' . $singular,
        'view_items'            => 'View ' . $plural,
        'search_items'          => 'Search ' . $plural,
        'not_found'             => 'No ' . strtolower( $plural ) . ' found.',
        'not_found_in_trash'    => 'No ' . strtolower( $plural ) . ' found in Trash.',
        'all_items'             => 'All ' . $plural,
        'archives'              => $singular . ' Archives',
        'attributes'            => $singular . ' Attributes',
        'insert_into_item'      => 'Insert into ' . strtolower( $singular ),
        'uploaded_to_this_item' => 'Uploaded to this ' . strtolower( $singular ),
        'filter_items_list'     => 'Filter ' . strtolower( $plural ) . ' list',
        'items_list'            => $plural . ' list',
        'item_published'        => $singular . ' published.',
        'item_updated'          => $singular . ' updated.',
        'item_scheduled'        => $singular . ' scheduled.',
        'menu_name'             => $plural,
        'name_admin_bar'        => $singular,
    );

    foreach ( $map as $key => $value ) {
        $labels->$key = $value;
    }

    return $labels;
} );