Add icons before entry meta - Author, Date & Comment ( Dashicons )

functions.php

/**
 * Update Search Nothing Found String and Search Input Box Placeholder Strings
 *
 * @param array $strings     List of default strings used in theme
 * @return array $strings
 */
function default_strings_callback( $strings ) {
    // Replace by with empty string.
	$strings['string-blog-meta-author-by']	= '';

    return $strings;
}

add_filter( 'astra_default_strings', 'default_strings_callback', 10 );

add_filter( 'astra_post_author', 'function_to_add_author_icon' ); 

function function_to_add_author_icon( $output ) {
	$output = '<span class="dashicons dashicons-admin-users"></span>' . $output;
	return $output;
}

add_filter( 'astra_post_date', 'function_to_add_post_date_icon' );

function function_to_add_post_date_icon( $output ) {
	$output = '<span class="dashicons dashicons-calendar-alt"></span>' . $output;
	return $output;
}

add_filter( 'astra_post_comments', 'function_to_add_post_comment_icon' );

function function_to_add_post_comment_icon( $output ) {

	if( ! empty( $output ) ) {
		$output = '<span class="dashicons dashicons-format-chat"></span>' . $output;
	}
	return $output;
}

add_filter( 'astra_post_meta_separator', 'astra_remove_meta_separator' );

function astra_remove_meta_separator( $separator ) {
	$separator = '|';
	return $separator;
}