[Brian]

A template is just a special kind of document.

Specifically, it opens up as "Untitled" so you can hit Save and give it a new name, without needing to worry about making changes, then hitting "Save" instead of "Save As" and putting all those changes into the original document.

For any given document, it's not that big a deal, but if your job involves making the same kind of document repeatedly, it can save you a lot of effort over time.