What is size pp means?

As an AI language model, I am not sure what you mean by "size pp." However, the acronym "pp" can refer to several things, including:

1. Pages - In this context, "size pp" could refer to the total number of pages in a document or book.

2. Parts Per Million - This unit of measurement is often used to indicate the concentration of a particular substance in a solution or mixture.

3. Personal Protective Equipment - "PP" can also stand for personal protective equipment, which encompasses clothing, helmets, goggles, or other garments or equipment to protect the wearer.

Without further context, it is not possible to provide more specific information about "size pp." Please provide more information or clarify your question.