QUESTION "meta id" OR "meta description"

[LogicPHP]

I have in Meta description, the following text: "Meta description example".

I want to extract the information from the "Meta description" and display it automatically, using the syntax:
<meta id="schema_description" itemprop="description" content="<?php function_exists('get_i18n_header') ? get_i18n_header(true,array('generator')) : get_header(); ?>">

But the extracted information appears as in the example below:
<meta id="schema_description" itemprop="description" content="<meta name="description" content="Meta description example" />

Does anyone know how to write this code syntax correctly?

How can I make this code, so that in the "content" section I can insert the existing information in the Meta description, only.