Example, I want to export org #+CATEGORY: Computer to html <meta name="category" content="Computer".

I custom define defun org-html-meta-tags-fancy (info) function.

 (let ((title (org-html-plain-text
                (org-element-interpret-data (plist-get info :title)) info))

        (category (org-html-plain-text
                   (org-element-interpret-data (plist-get info :category)) info))

        (author (and (plist-get info :with-author)
                     (let ((auth (plist-get info :author)))
                       ;; Return raw Org syntax.
                       (and auth (org-html-plain-text
                                  (org-element-interpret-data auth) info))))))

then (message "%s" category),,it’s null.

#+AUTHOR: author name
#+DESCRIPTION: Description
#+KEYWORDS: KeyWord
#+CATEGORY: Computer

why description, author and keywords can export?

Emacs Version: 29.4
Org-Mode Version: 9.6.15