Page numbers are a section property, so one solution is to insert section
breaks around the page where you don't want numbering and remove the PAGE
field from the header/footer in that section after unlinking it from the
previous and following sections (see
http://word.mvps.org/FAQs/Numbering/PageNumbering.htm).

But there are other solutions as well. Sometimes using "Different first
page" will accomplish what you want; see
http://sbarnhill.mvps.org/WordFAQs/HeaderFooter.htm. Or if you want to skip
numbering for a specific page where the page number is known but section
breaks would be awkward, you can use a field such as { IF { PAGE } = x ""
"{ PAGE }" }, which tells Word to put nothing if the page number matches the
one you've specified (x) and otherwise to print the page number.