what does the rolling/loading icon mean?

It means that your iPhone is downloading or uploading data from a network (Wi-Fi or Cellular.) It's not easy to know which app is doing it but, usually, it's the app you have open on your screen.

For instance, when using Safari, you'll see this icon when Safari is connecting to a website.

This icon disappears once data is no longer transmitted between your iPhone and the network.

Hello.

Refer to the comment above, as it is very helpful. But, since it looks like something is loading, you may want to plug in to power and connect to WiFi so that it can finish loading whatever it is loading.

Hope this helps.