The word gut refers to a part of the body, but it has some metaphorical meanings, too. Your “gut” is your stomach. Some men have a “beer gut” (a big stomach from drinking too much beer!) and some people talk about wanting to do exercise to “lose their gut” (make their stomach smaller).
We also have the expressions gut reaction or gut feelings. These are feelings you have when you are certain that you’re correct, but you can’t explain why logically. It’s just a strong feeling from deep inside you. For example:
Guts in the plural form refers to the inside of your stomach – your intestines and internal organs. But it’s also used to mean courage or bravery. If someone “has the guts to do something,” then they have enough courage to do it: