Lots! The exact number depends on which translation, which size and which kind you have.
Around 80,000 different versions of the Bible are sold each year. There are 900 versions just in English, but you'll find versions in over 2,000 different languages. As well as the language, the style and font size will change the number of pages. Bibles range from small pocket Bibles to big study Bibles that have lots of extra pages for pictures, maps and explanations of scripture.
A Bible can therefore have anything between a few hundred to a few thousand pages, depending on which one you choose.