"Otherwise" is used to offer an alternative situation. It’s very similar to "or " and "or else."
1. Today is a holiday; otherwise, he would be at work.
2. In ancient times, it was necessary for a man to learn how to defend himself; otherwise, he was easily killed by other men.
3. Traffic is really bad right now; otherwise, she’d be at work already.
4. Sometimes it’s a good idea to throw out food or beverages that are really old or smell bad. You might get sick otherwise.
5. It’s important for children to get a good early education; otherwise, they might have problems in school later on.
6. She makes a good living from her artwork; otherwise, she would have to work on her family’s farm.
7. Human beings have a responsibility to protect animals that are in danger of becoming extinct. We can not do otherwise.