I have an iPhone 5 with a arrow at the top

Hi. I have a clear arrow on the top right hand side next to the battery, nothing is left open on my phone yet it is still there. Can anyone help please

That's the navigation symbol like maps

That means you have some app or service, maybe in the background, which is using location services.

Some apps use location services to find out where you are so they can give you better info (for instance, maps, or an app that shows restaurants near you).

You can turn this off to save battery or if you believe it will increase your privacy. To do that, go to Settings > Privacy > Location services.

P.S. Location services don't necessarily use a lot of battery. Your phone can determine it's approximate location using cell phone towers and nearby Wi-Fi networks, without using much battery. However, if your phone needs a very accurate location (it depends on the app), then it will use GPS, which will use more battery.