EXCERPT SIMPLIFIED IN WORDPRESS THEME DEVELOPMENT

Excerpt is the short form of the whole article. If you want to get the whole article inside the loop you need to echo the tag get_the_content(), but to get short form or the article you can do two method.

FIRST AND EASY METHOD
you can simply echo get_the_excerpt();

SECOND METHOD BUT FLEXIBLE METHOD
you can abridge as much words as you like in this method. The syntax is as follow
$article_data = strip_tags(substr(get_the_content(), 0, 500));
echo $article_data.’ ….’;