1. In questions (present simple, 3rd person singular):
* Does she like pizza?
* Does the train leave at 5pm?
* Does he know how to swim?
2. In negative statements (present simple, 3rd person singular):
* She does not like spicy food. (Or, she doesn't like spicy food.)
* The cat does not sleep in the bed. (Or, the cat doesn't sleep in the bed.)
* He does not understand the instructions. (Or, he doesn't understand the instructions.)
3. To emphasize an action (present simple, 3rd person singular):
* He does know the answer, but he's not telling.
* She does enjoy cooking, even if she doesn't always have the time.
* It does matter to me what you think.
4. To make a statement about a habitual action (present simple, 3rd person singular):
* She does her homework every night.
* The sun does rise in the east.
* He does go to the gym three times a week.
5. In short answers:
* Does he play the piano? Yes, he does.
* Does she speak French? No, she doesn't.
Remember that "does" is used with the third person singular subjects (he, she, it). For other subjects, use "do".