skip tag is used in several tasks. It is available to use only when hook description for a task says so. Its purpose is to skip actions if certain conditions are met.

For example in task Export customers to FTP, we automatically export every new customer to our FTP. We might want to skip exporting the customer if the new customer does not have first name.

To do so we would set up Before Action hook with following code:

{% if customer.first_name == blank %}
{% skip %}
{% endif %}

In above example, for any customer with blank email, we will skip our action (which is creating csv with customer and uploading it to FTP).