A time when you demonstrated teamwork?

This can be answered a number of different ways. You could describe...

-a time when your place of business was shortstaffed or a team deadline was going to be difficult to meet, and you (and maybe others) put in extra time to complete a project.

-a time when your place of business needed someone to volunteer for a particular task--here you would explain why you volunteered, other than wanting to assist...you could say you want to keep busy, you had the skillset necessary or the leadership skills, etc. This would be a great one because it shows off your other qualities.

-a time when you worked unusual/irregular/overnight shifts because it was necessary.

-a time when you did the duties of another position than your own because it was needed.

And there's probably many more. They are asking how you went the extra mile for your company---how did you go beyond what is generally required of you in your position? This demonstrates that you are a team player who is willing to do what is reasonably necessary to help your company AKA your "team."

They can be looking for various things.
Here are some:
- Deliver something that contributes to a bigger deliverable.
- Work well with other people.
- Delegate or commit when something gets delegated to you.
- Your ability to give input into decisions.
- Your ability to compromise for the greater good and not be stubborn.
Cheers