Wordpress - create a custom sidebar

//functions.php
add_action( 'widgets_init', 'theme_slug_widgets_init' );
function theme_slug_widgets_init() {
    register_sidebar( array(
        'name' => __( 'Sidebar for Blog', 'theme-slug' ),
        'id' => 'sidebar-blog',
        'description' => __( 'Widgets in this area will be shown only on blog pages.', 'theme-slug' ),
        'before_widget' => '<li id="%1$s" class="widget %2$s">',
	'after_widget'  => '</li>',
	'before_title'  => '<h2 class="widgettitle">',
	'after_title'   => '</h2>',
    ) );
}

//sidebar.php
<?php

$position   = isset( $position ) ? $position : 'right';
$section    = isset( $section ) ? $section : 'blog';
$size       = isset( $size ) ? $size : '4';
$display    = isset( $display ) ? $display : 'desktop';

?>
<div class="fl-sidebar fl-sidebar-<?php echo $position; ?> fl-sidebar-display-<?php echo $display; ?> col-md-<?php echo $size; ?>" itemscope="itemscope" itemtype="https://schema.org/WPSideBar">
	<?php do_action( 'fl_sidebar_open' ); ?>

	<?php //dynamic_sidebar( $section . '-sidebar' ); ?>
	<?php 
	if( is_singular( 'blog' ) || is_taxonomy( 'blog_category' ) ){
  
		   
		    dynamic_sidebar( 'sidebar-blog' );  
		  
		  }
		  else {
		  	dynamic_sidebar( $section . '-sidebar' );
	}

	

	?>

	<?php do_action( 'fl_sidebar_close' ); ?>
</div>