single_month_title( string $prefix = '', bool $display = true )

Source

File: wp-includes/general-template.php

function single_month_title( $prefix = '', $display = true ) {
	global $wp_locale;

	$m        = get_query_var( 'm' );
	$year     = get_query_var( 'year' );
	$monthnum = get_query_var( 'monthnum' );

	if ( ! empty( $monthnum ) && ! empty( $year ) ) {
		$my_year  = $year;
		$my_month = $wp_locale->get_month( $monthnum );
	} elseif ( ! empty( $m ) ) {
		$my_year  = substr( $m, 0, 4 );
		$my_month = $wp_locale->get_month( substr( $m, 4, 2 ) );
	}

	if ( empty( $my_month ) ) {
		return false;
	}

	$result = $prefix . $my_month . $prefix . $my_year;

	if ( ! $display ) {
		return $result;
	}
	echo $result;
}