You didn't tell us if you're on a Mac or a PC, which would have made a big difference -- so I'll just give you instructions either way.
1. Compliment your friend on their taste and intelligence in using such a fine program as Pages on a Mac. Truly the mark of a sophisticated and erudite chum.
2. Ask them kindly if they could possibly re-send the document to you as a Word file, since that is one of the export options in Pages, and then e-mail you that instead.
You could alternatively (if you're on a Mac) download the free 30-day trial of iWork, whereupon you too would discover the elegance and sophistication that distinguishes Pages (and Keynote, and even Numbers) from the dreary and cubicle-like Office (which, though a very capable suite indeed, lacks any sense of style or joi d'vie). This would open the Pages document you were sent and you could either work with it there or convert it to a Word document yourself. Hope that helps.