The detection 'W97M.Downloader.[variant]' identifies malicious macro code embedded in a Microsoft Word document file. This file is usually distributed as an attachment to an email message.
The 'bait' Word document file will typically be crafted to look legitimate and appealing to a user (for example, pretending to be a resume or containing interesting news items or content), so that they are drawn into opening the file.
Once the file is opened, the malicious macro code embedded in the file is launched. Typically, the macro's malicious actions will silently take place in the background, evading the user's notice.
The specific malicious actions performed by the macro will differ by variant, but usually involve downloading and installing additional malicious files onto the affected machine. For an example of a Downloader variant and its behavior, see: