The equals sign means is equal to. It is telling us that one thing equates to another; that they are the same.
The iPhone 4 is the most recent iPhone to be discontinued from the iOS Update cycle. It did not receive the iOS 8 update, so it's final software version is iOS 7.1.2. You can update to this version through iTunes, or download it from an IPSW repository like this website: https://ipsw.me/.
With this in mind, we consider what lies ahead in their next device: the iPhone 8. Because 2017 is the 10th anniversary of the iPhone, Apple has ambitious plans in store. The iPhone 8 is rumored to have an edge-to-edge display, no home button, and support wireless charging.