I have an external hard drive that has backed up my old Lightroom catalog, I assume it contains the keywords. I need the key words to be restored onto a new catalog on my computer's hard drive. How is that done? I have a Mac.
If you switching your computer and want the Lightroom on the new machine, then the best practice is to copy the old catalog( contains edits, keywords, previews etc) to new system and simply open it and continue working on it.
Similar discussion: How do I transfer keywords in Lightroom from one computer to another?
I cannot imagine it is that simple but will try. Thanks