Shortcode is a general concept used with all WordPress plugins.
Basically, a shortcode is a piece of code that you put in any part of the text and that will be replaced by the real content when you see the web page.
This piece of code is pre-determined by the plugin. There are plugins with shortcodes available for use and plugins without shortcodes.
You have to follow the instructions of each plugin because each shortcode has your own syntax.
Example:
In this example, was used a shortcode provided by weDocs plugin. A plugin used to build FAQ/documentation.
The default shortcode is [wedocs], used to show all active documentation.
But in the plugin documentation we can check if we put [wedocs col=”3″] the documentation will be shown as an index with 3 columns.