expand-abbrev is an interactive and byte-compiled function defined in
abbrev.el.gz.

Signature
(expand-abbrev)

Documentation
Expand the abbrev before point, if there is an abbrev there.

Effective when explicitly called even when abbrev-mode is nil.
Calls the value of abbrev-expand-function with no argument to do
the work, and returns whatever it does.  (That return value should
be the abbrev symbol if expansion occurred, else nil.)

View in manual

Key Bindings
abbrev-map '
abbrev-map e
ctl-x-map '
ctl-x-map a '
ctl-x-map a e
global-map C-x '
global-map C-x a '
global-map C-x a e

References
References in abbrev.el.gz:
(defun inverse-add-abbrev ...)    1 reference
(defun abbrev-prefix-mark ...)    1 reference
(defun expand-region-abbrevs ...) 1 reference

Find all references Functions used by expand-abbrev

Debugging
Enable edebug Enable tracing
Disassemble Forget

Source Code
;; Defined in /usr/share/emacs/29.4/lisp/abbrev.el.gz
(defun expand-abbrev ()
  "Expand the abbrev before point, if there is an abbrev there.
Effective when explicitly called even when `abbrev-mode' is nil.
Calls the value of `abbrev-expand-function' with no argument to do
the work, and returns whatever it does.  (That return value should
be the abbrev symbol if expansion occurred, else nil.)"
  (interactive)
  (or (funcall abbrev-expand-function)
      (if abbrev-suggest
          (abbrev--suggest-maybe-suggest))))

Symbol Properties
event-symbol-element-mask
  (expand-abbrev 0)
event-symbol-elements
  (expand-abbrev)
modifier-cache
  ((0 . expand-abbrev))