An upstanding person is someone who behaves well and tries to do what's right. They often have good values and don't take part in bad things.
The word "upstanding" is often used to describe people, especially if they're leaders or role models. For example, a politician might be praised for being an upstanding leader who makes fair decisions and serves their community well. You could also use the word to talk about someone's behavior - like saying a student showed up to school on time every day because she was an upstanding member of her class. Sometimes "upstanding" can refer to something that's solidly built or has good foundations, but this is less common than using it to describe people and their actions.
Honest; reputable; respectable
Example: An upstanding merchant will exchange a faulty product.
