Word is part of MS Office, and is not included with Windows. Wordpad is included with windows. Office runs on several platforms, including Windows.
You may have an Office 365 subscription. Office is moving to a subscription model (as is Windows). Formerly, you could purchase a full retail copy of Office; now, it's usually a subscription. The good thing about the subscription, is that you can always download the current version. That's about the only good thing.
When you open Word, it likely says Office 365, depending on the version.
New computers do come with a trial for MS Office installed. You can log on to your subscription, buy Office, enter your product key, or ignore it.
There is a free alternative, called Open Office. It's clunky, and has some compatibility issues.