There is a Mac version of Office. If you have a legitimate copy for Windows, contact Microsoft about doing a cross platform upgrade. I think you can get the Mac version for the same price as the upgrade version.
I suggest looking at two alternatives.
1) Apple's iWork suite. It comes with Pages for word processing, Numbers for spread sheets, and Keynote for presentations. Each will import and export to Office formats. iWork costs $80 - or $100 for a "family license". I use iWork for most of my office needs. The only exception is for a large set of Word documents that I copy and paste into Dreamweaver. Pages does not copy the formatting like Word does. When I copy from Word, I spend less time tweaking the formatting of the text.
2) OpenOffice, is a free suite that will open and save office files. I used OpenOffice for a while and although it worked well, I found it to be a be awkward for what I was used to. If I hadn't had Office or iWork to fall back on, I'm sure that I would have because accustomed to OpenOffice in short order.
And to clear the air of BS:
Don't believe the clueless people who tell you that a Mac is nothing but a PC that runs Mac OS. This lie comes from the idea that is a Mac uses an Intel processor, then it is the same as a PC. Using this logic, the Nintendo Game Cube and the Wii must be Power Macs, since they use the Power PC chip. Oh yeah, and the Vehicle-Management computer for the F-35 fighter Jet is also a Power Mac since it uses a Power PC chip.
Apple is no longer innovative? Where does that come from? The Dell Envy and the Sony Vaio both copy Mac notebooks. Apple brought us the first true smart phone, which is now being copied by three companies. Apple is the first (and only) company that makes an MP3 player with a video camera. Apple is the first to make a notebook with a multi-touch trackpad. Apple was the first company to make wi-fi standard on all computers and the company that made wi-fi and a standard. Microsoft is the company that takes feature bloat and feature cloning to an art form.
Windows is just as proprietary as Mac OS. You can run only Windows software on Windows. Apple branded software amounts to about 5% of all software titles that you can run in Mac OS. You are not tied into Apple software. You have just as much freedom of choice with the Mac as you do with Windows. A Mac with the same specs (not just CPU, RAM, and Hard drive) as a PC is faster - as proven by PC Magazine. It is also cheaper - as proven by anyone who knows how to compare the two after adding to the PC to make it the same as the Mac.
Don't believe the lies.