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/.
For completeness, Iâll compare both of these models to the iPhone 5. The iPhone 4 is a two-year old design, the 4S is last years model, and the iPhone 5 is the latest model. With each year, Apple provided a faster processor in the iPhone and the speed difference is noticeable between each model.