noun
number of pages; page count
Refers to the total number of pages in a book, document, or other paginated material.
この本のページ数は300ページです。
This book has 300 pages.
レポートのページ数が足りない。
The report doesn't have enough pages.
ページ means 'page' (a single sheet or side), while ページ数 refers to the count or number of pages.
Compound of ページ (page, from English) and 数 (number, count).