There are two kinds of keywords in Lightroom Classic. These are People keywords and Things keywords.
When a the face of a person is detected in Lightroom Classic, the program will draw a rectangle around the face and will put a question mark in the name field. The rectangles are visible in the Loupe view and when the face rectangle view icon is selected. This rectangles may also be made visible under the menu /Photo/People/Draw Face Regions.
If you have enabled Edit/Catalog/Automatically write changes to XMP, and there is a keyword change, then Lightroom Classic will write the metadata to the file on the hard drive. So if I have a rectangle and put in the name “Richard Lyman”, then Lightroom will make a keyword and write the name and rectangle to the file on the hard drive as a Metadata Working Group Region. The FaceTags plugin in Photoshop will now be able to use that rectangle for creating Graphic Information Format, GIFs, or face tag labels.
In the course of many years of collecting family photos and transitioning through several Microsoft and Adobe applications, the metadata can get messed up. When the FaceTags plugin runs on a folder, it will analyze the metadata and make recommendations for cleaning this up. The plugin also makes a batch file that can be used to apply some of the recommendations.
The recommendations should be run on a copy of your original photos. It only takes a couple of seconds to type control C, control V to copy your photo tree. Exiftool must be installed somewhere in the operating system environment path in order to run the exiftool commands in the recommendations. It can be placed in the Windows folder, for instance. Exiftool leaves the original files with the _original suffix so they never can be lost, although it can be a pain to rename them back to their original names. Therefore it is best to experiment on the copy of your photo tree when running the recommendations.bat file.