What type of sentence is this?

On July 4, 1976, the nation’s bicentennial, 10,741 American flags were flown over the U.S. Capitol, the largest number ever flown there in one day.

It's a simple sentence with two appositives.

Can you please help me with my english essay?

Of course! I'd be happy to help you with your English essay. Please provide me with the details of your essay topic and any specific questions or areas you would like assistance with.