Sidebar single post php code

Hi, I’ve never written code before but read a few posts and am trying to get the sidebar to appear in single post pages. Here’s the code that was in the single.php before I changed it:

<?php

/*
 * The Template for displaying all single posts.
 *
 * lambda framework v 1.0
 * by www.unitedthemes.com
 * since lambda framework v 1.0
 */

global $lambda_meta_data;
$meta_sidebar = $lambda_meta_data->get_the_value('sidebar');

get_header();
if($meta_sidebar != UT_THEME_INITIAL.'sidebar_none') {
	st_before_content($columns='');

} elseif($meta_sidebar == UT_THEME_INITIAL.'sidebar_none') {

	st_before_content($columns='sixteen');

}

get_template_part( 'loop', 'single' );
st_after_content();
if($meta_sidebar) {
	get_sidebar();
} 

get_footer();
?>

And here is what I changed it to. Notice I removed “_none”

<?php

/*
 * The Template for displaying all single posts.
 *
 * lambda framework v 1.0
 * by www.unitedthemes.com
 * since lambda framework v 1.0
 */

global $lambda_meta_data;
$meta_sidebar = $lambda_meta_data->get_the_value('sidebar') after elseif section:

get_header();
if($meta_sidebar != UT_THEME_INITIAL.'sidebar_none') {
	st_before_content($columns='');

} elseif($meta_sidebar == UT_THEME_INITIAL.'sidebar') {

	st_before_content($columns='sixteen');

}

get_template_part( 'loop', 'single' );
st_after_content();
if($meta_sidebar) {
	get_sidebar();
} 

get_footer();
?>

[Please use the code buttons NOT blockquote buttons for posting code]

Did I do it correctly? What does the “if” “else if” part mean?

Here’s my site: https://www.thehoundstoothblog.com