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/.
[...] [Apple] will have the most expensive phone, by far, in the marketplace. There's no chance that the iPhone is going to get any significant market share. No chance. On February 5, 2008, Greg Joswiack, vice president of Worldwide iPod and iPhone Product Marketing, announced a 16GB model.