count-words-region

count-words-region is an interactive compiled Lisp function in `simple.el'.

It is bound to M-=.

(count-words-region START END &optional ARG)

Count the number of words in the region.
If called interactively, print a message reporting the number of
lines, words, and characters in the region (whether or not the
region is active); with prefix ARG, report for the entire buffer
rather than the region.

If called from Lisp, return the number of words between positions
START and END.