What does feces do in the digestive system?

Answer 1

The rectum is a pouch at the end of the large intestine. The role of the rectum is to store feces for immediate expulsion from the body. So the feces just sits there until the person goes to the toilet.

Answer 2

It doesn't "do" much of anything; it's what's left over after the nutrients have been extracted. A substantial amount of feces is also composed of the remains of bacteria that live in the gut, and these do do (no pun intended) something; they're symbionts that break down molecules that we can't ourselves, or in some cases even produce vital nutrients ... vitamin B12 is a good example.