electric-pair-mode is an interactive autoloaded Lisp function in `elec-pair.el'.

(electric-pair-mode &optional ARG)

Toggle automatic parens pairing (Electric Pair mode).
With a prefix argument ARG, enable Electric Pair mode if ARG is
positive, and disable it otherwise. If called from Lisp, enable
the mode if ARG is omitted or nil.

Electric Pair mode is a global minor mode. When enabled, typing
an open parenthesis automatically inserts the corresponding
closing parenthesis. (Likewise for brackets, etc.).