Saving something from the browser to Google Drive normally means downloading it first, then uploading it through Drive's website. A save to Google Drive extension skips that step, adding a right-click option or a redirect for downloads so files, images and pages go straight into a chosen Drive folder.
Saving webpages and files directly
Look for an extension that adds a right-click menu option on images, links and pages, sending them to Drive without a manual download and upload. Some can also intercept regular downloads and redirect them to a Drive folder instead of your computer's downloads folder.
Choosing the right Drive folder
A useful save extension lets you pick or create a destination folder at the time you save, rather than dumping everything into the root of your Drive. Check whether it remembers your last used folder or lets you set a default, since sorting files afterward is tedious.
Account access and permissions to check
Since this type of extension needs access to your Google Drive, check exactly which permission it requests: ideally file-level access to files it creates, not full access to your entire Drive. Review the permission screen Google shows during installation before granting access.