The empire view gives you an overview of all of your planets and moons.
You can click “Crawl” to crawl all the information of all of your planets/moons. This is ensure that all information are accurate.
You can click “Reorder planets” button if you don’t like the current order. You will have to drag and drop the planets in the order you want them to appear.
You can click on a planet to go to that planet page.
If you click on a building:
You can “Build” it right away if you have enough resources.
Or you can “Import resources & build” to import resources from the home planet, and then build the selected building when the resources arrives.
Or you can “Add to queue” to add to the planet’s build queue.