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/.
The iPhone 7 and 7 Plus are Apple's newest iPhones, with significant camera improvements, a new glossy black color, better battery life, faster processors, and improved water resistance implemented through a click-less haptic home button and no headphone jack. The new iPhones launched on September 16, 2016.